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          <h2>Python Overview</h2>
          <br />
          <h3>What is Python</h3>
          <br />
          <li>
            Python is a dynamically typed, General Purpose Programming
            Language that supports an object-oriented programming approach as
            well as a functional programming approach.
          </li>
          <li>
            Python is also an interpreted and high-level programming language.
          </li>
          <li>It was created by Guido Van Rossum in 1989.</li>
          <br /><br />
          <h3>Features of Python</h3>
          <br />
          <li>Python is simple and easy to understand.</li>
          <li>
            It is Interpreted and platform-independent which makes debugging
            very easy.
          </li>
          <li>Python is an open-source programming language.</li>
          <li>
            Python provides very big library support. Some of the popular
            libraries include NumPy, Tensorflow, Selenium, OpenCV, etc.
          </li>
          <li>
            It is possible to integrate other programming languages within
            python.
          </li>
          <br />
          <br />
          <h3>What is Python used for</h3>
          <br />
          <li>
            Python is used in Data Visualization to create plots and graphical
            representations.
          </li>
          <li>
            Python helps in Data Analytics to analyze and understand raw data
            for insights and trends.
          </li>
          <li>
            It is used in AI and Machine Learning to simulate human behavior
            and to learn from past data without hard coding.
          </li>
          <li>It is used to create web applications.</li>
          <li>It can be used to handle databases.</li>
          <li>
            It is used in business and accounting to perform complex
            mathematical operations along with quantitative and qualitative
            analysis.
          </li>
          <br />
          <br />
        </div>
        <div class="notes" id="div2" style="display: none">
          <h2>Installation & Getting Started</h2>
          <br />
          <h3>Steps to Install Python:</h3>
          <br />
          <li>
            Visit the official python website:
            <a href="https://www.python.org/" target="_blank">https://www.python.org/</a>
          </li>
          <li>
            Download the executable file based on your Operating System and
            version specifications.
          </li>
          <li>
            Run the executable file and complete the installation process.
          </li>
          <br />
          <h3>Version:</h3>
          <br />
          <p>
            After installation check the version of python by typing following
            command: ‘python --version’.
          </p>
          <br />
          <br />
          <h3>Starting Python:</h3>
          <br />
          <p>
            Open Python IDE or any other text editor of your preferred choice.
            Let’s understand python code execution with the simplest print
            statement. Type the following in the IDE:
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        print("Hello World !!!")
    </code>
    </pre>
          <br />
          <br />
          <p>
            Now save the file with a .py extension and Run it. You will get
            the following output:
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello World !!!
    </code>
    </pre>
          <br />
          <br />
          <h3>Installing Packages:</h3>
          <br />
          <p>
            To install packages in Python, we use the pip command. <br />
            e.g. pip install "Package Name"
            <br />
            Following command installs pandas package in Python
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        print("Hello World !!!")
    </code>
    </pre>
          <br />
          <br />
          <p>
            We will learn more about the pip command in the chapter dedicated
            to pip.
          </p>
          <br />
          <br />
        </div>
        <div class="notes" id="div3" style="display: none">
          <h2>What is Syntax?</h2>
          <br />
          <p>
            In simplest words, Syntax is the arrangement of words and phrases
            to create well-formed sentences in a language. In the case of a
            computer language, the syntax is the structural arrangement of
            comments, variables, numbers, operators, statements, loops,
            functions, classes, objects, etc. which helps us understand the
            meaning or semantics of a computer language.
          </p>
          <br />
          <br />
          <p>
            For E.g. a ‘comment’ is used to explain the functioning of a block
            of code. It starts with a ‘#’.
            <br />
            More on comments in the comments chapter.
          </p>
          <br />
          <br />
          <p>
            For E.g. a block of code is identified by an ‘indentation’. Have a
            look at the following code, here print(i) is said to be indented
            with respect to the link above it. In simple words, indentation is
            the addition of spaces before the line "print(i)"
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        for i in range(5):
        print(i)   
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div4" style="display: none">
          <h2>Python Comments</h2>
          <br />
          <p>
            A comment is a part of the coding file that the programmer does
            not want to execute, rather the programmer uses it to either
            explain a block of code or to avoid the execution of a specific
            part of code while testing.
          </p>
          <br />
          <br />
          <h3>Single-Line Comments:</h3>
          <br />
          <p>To write a comment just add a ‘#’ at the start of the line.</p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #This is a 'Single-Line Comment'
        print("This is a print statement.")   
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        This is a print statement. 
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        print("Hello World !!!") #Printing Hello World  
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello World !!!
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 3:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        print("Python Program")
        #print("Python Program") 
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Python Program
    </code>
    </pre>
          <br />
          <br />
          <h3>Multi-Line Comments:</h3>
          <br />
          <p>
            To write multi-line comments you can use ‘#’ at each line or you
            can use the multiline string.
          </p>
          <br />
          <p><b>Example 1:</b> The use of ‘#’.</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #It will execute a block of code if a specified condition is true.
        #If the codition is false than it will execute another block of code.
        p = 7
        if (p > 5):
            print("p is greater than 5.")
        else:
            print("p is not greater than 5.")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        p is greater than 5.
    </code>
    </pre>
          <br />
          <br />
          <p><b>Example 2:</b> The use of multiline string.</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        """This is an if-else statement.
        It will execute a block of code if a specified condition is true.
        If the condition is false then it will execute another block of code."""
        p = 7
        if (p > 5):
            print("p is greater than 5.")
        else:
            print("p is not greater than 5.")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        p is greater than 5.
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div5" style="display: none">
          <h2>Python Variables</h2>
          <br />
          <p>
            Variables are containers that store information that can be
            manipulated and referenced later by the programmer within the
            code.
            <br />
            In python, the programmer does not need to declare the variable
            type explicitly, we just need to assign the value to the variable.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        name = "Abhishek"   #type str
        age = 20            #type int
        passed = True       #type bool
    </code>
    </pre>
          <br />
          <br />
          <p>
            It is always advisable to keep variable names descriptive and to
            follow a set of conventions while creating variables:
          </p>
          <br />
          <li>
            Variable name can only contain alpha-numeric characters and
            underscores (A-z, 0-9, and _ )
          </li>
          <li>
            Variable name must start with a letter or the underscore
            character.
          </li>
          <li>Variables are case sensitive.</li>
          <li>Variable name cannot start with a number.</li>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Color = "yellow"    #valid variable name
        cOlor = "red"       #valid variable name
        _color = "blue"     #valid variable name

        5color = "green"    #invalid variable name
        $color = "orange"   #invalid variable name
    </code>
    </pre>
          <br />
          <br />
          <p>
            Sometimes, a multi-word variable name can be difficult to read by
            the reader. To make it more readable, the programmer can do the
            following:
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        NameOfCity = "Mumbai"       #Pascal case
        nameOfCity = "Berlin"       #Camel case
        name_of_city = "Moscow"     #snake case
    </code>
    </pre>
          <br />
          <br />
          <h3>Scope of variable:</h3>
          <br />
          <p>
            The scope of the variable is the area within which the variable
            has been created. Based on this a variable can either have a local
            scope or a global scope.
          </p>
          <br />
          <br />
          <h3>Local Variable:</h3>
          <br />
          <p>
            A local variable is created within a function and can be only used
            inside that function. Such a variable has a local scope.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        icecream = "Vanilla"    #global variable
def foods():
    vegetable = "Potato"    #local variable
    fruit = "Lichi"         #local variable
    print(vegetable + " is a local variable value.")
    print(icecream + " is a global variable value.")
    print(fruit + " is a local variable value.")

foods()
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Potato is a local variable value.
        Vanilla is a global variable value.
        Lichi is a local variable value.
    </code>
    </pre>
          <br />
          <br />
          <h3>Global Variable:</h3>
          <br />
          <p>
            A global variable is created in the main body of the code and can
            be used anywhere within the code. Such a variable has a global
            scope.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        icecream = "Vanilla"    #global variable
def foods():
    vegetable = "Potato"    #local variable
    fruit = "Lichi"         #local variable
    print(vegetable + " is a local variable value.")
foods()
print(icecream + " is a global variable value.")
print(fruit + " is a local variable value.")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Potato is a local variable value.
        Vanilla is a global variable value.
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div6" style="display: none">
          <h2>Data Types</h2>
          <br />
          <p>
            Data type specifies the type of value a variable requires to do
            various operations without causing an error. By default, python
            provides the following built-in data types:
          </p>
          <br />
          <h3>Numeric data: int, float, complex</h3>
          <br />
          <p>
            int: 3, -8, 0
            <br />
            float: 7.349, -9.0, 0.0000001
            <br />
            complex: 6 + 2i
            <br />
            more on numeric data types in the number chapter.
          </p>
          <br />
          <br />
          <h3>Text data: str</h3>
          <br />
          <p>str: “Hello World!!!”, “Python Programming”</p>
          <br />
          <br />
          <h3>Boolean data:</h3>
          <br />
          <p>Boolean data consists of values True or False.</p>
          <br /><br />
          <h3>Sequenced data: list, tuple, range</h3>
          <br />
          <p>
            <b>List:</b> A list is an ordered collection of data with elements
            separated by a comma and enclosed within square brackets. Lists
            are mutable and can be modified after creation.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        list1 = [8, 2.3, [-4, 5], ["apple", "banana"]]
        print(list1)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        [8, 2.3, [-4, 5], ['apple', 'banana']]
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>tuple:</b>A tuple is an ordered collection of data with
            elements separated by a comma and enclosed within parentheses.
            Tuples are immutable and can not be modified after creation.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        tuple1 = (("parrot", "sparrow"), ("Lion", "Tiger"))
        print(tuple1)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        (('parrot', 'sparrow'), ('Lion', 'Tiger'))
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>range:</b>returns a sequence of numbers as specified by the
            user. If not specified by the user then it starts from 0 by
            default and increments by 1.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        sequence1 = range(4,14,2)
        for i in sequence1:
            print(i)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        4
        6
        8
        10
        12
    </code>
    </pre>
          <br />
          <br />
          <h3>Mapped data: dict</h3>
          <br />
          <p>
            <b>dict:</b> a dictionary is an unordered collection of data
            containing a key:value pair. The key:value pairs are enclosed
            within curly brackets.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        dict1 = {"name":"sweety", "age":20, "canVote":True}
        print(dict1)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'name': 'sweety', 'age': 20, 'canvote': True}
    </code>
    </pre>
          <br />
          <br />
          <h3>Binary data: bytes, bytearray, memoryview</h3>
          <br />
          <p>
            <b>bytes:</b>bytes() function is used to convert objects into byte
            objects, or create empty bytes object of the specified size.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #Converting string to bytes
        str1 = "This is a string"
        arr1 = bytes(str1, 'utf-8')
        print(arr1)
        arr2 = bytes(str1, 'utf-16')
        print(arr2)
        
        #Creating bytes of given size
        bytestr = bytes(4)
        print(bytestr)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        b'This is a string'
        b'\xff\xfeT\x00h\x00i\x00s\x00 \x00i\x00s\x00 \x00a\x00 \x00s\x00t\x00r\x00i\x00n\x00g\x00'
        b'\x00\x00\x00\x00'
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>bytearray:</b> bytearray() function is used to convert objects
            into bytearray objects, or create empty bytearray object of the
            specified size.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #Converting string to bytes
        str1 = "This is a string"
        arr1 = bytearray(str1, 'utf-8')
        print(arr1)
        arr2 = bytearray(str1, 'utf-16')
        print(arr2)

        #Creating bytes of given size
        bytestr = bytearray(4)
        print(bytestr)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        bytearray(b'This is a string')
        bytearray(b'\xff\xfeT\x00h\x00i\x00s\x00 \x00i\x00s\x00 \x00a\x00 \x00s\x00t\x00r\x00i\x00n\x00g\x00')
        bytearray(b'\x00\x00\x00\x00')
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>memoryview:</b>memoryview() function returns a memory view
            object from a specified object.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = bytes("home", "utf-8")
        memoryviewstr = memoryview(str1)
        print(list(memoryviewstr[0:]))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        [104, 111, 109, 101]
    </code>
    </pre>
          <br />
          <br />
          <h3>Set data:</h3>
          <br />
          <p>
            Set is an unordered collection of elements in which no element is
            repeated. The elements of sets are separated by a comma and
            contained within curly braces.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        set1 = {4, -5, 8, 3, 2.9}
        print(set1)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {2.9, 3, 4, 8, -5}
    </code>
    </pre>
          <br />
          <br />
          <h3>None:</h3>
          <br />
          <p>
            None is used to define a null value. When we assign a None value
            to a variable, we are essentially resetting it to its original
            empty state which is not the same as zero, an empty string or a
            False value.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        state = None
        print(type(state))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        &lt;class 'NoneType'&gt;
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div7" style="display: none">
          <h2>Python Numbers</h2>
          <br />
          <p>In Python, numbers are of the following data types:</p>
          <br />
          <li>int</li>
          <li>float</li>
          <li>complex</li>
          <br />
          <br />
          <h3>int</h3>
          <br />
          <p>
            int is a positive or a negative integer of any length. int should
            not be a decimal or a fraction.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        int1 = -2345698
        int2 = 0
        int3 = 100548
        
        print(type(int1))
        print(type(int2))
        print(type(int3))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        &lt;class 'int'&gt;
        &lt;class 'int'&gt;
        &lt;class 'int'&gt;
    </code>
    </pre>
          <br />
          <br />
          <h3>Float</h3>
          <br />
          <p>
            A float is a positive or a negative decimal number. It can be an
            exponential number or a fraction.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        flt1 = -8.35245     #decimal number
        flt2 = 0.000001     #decimal number
        flt3 = 2.6E44       #exponential number
        flt4 = -6.022e23    #exponential number
        
        print(type(flt1))
        print(type(flt2))
        print(type(flt3))
        print(type(flt4))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        &lt;class 'float'&gt;
        &lt;class 'float'&gt;
        &lt;class 'float'&gt;
        &lt;class 'float'&gt;
    </code>
    </pre>
          <br />
          <br />
          <h3>Complex</h3>
          <br />
          <p>
            Complex numbers are a combination of real and imaginary number.
            They are of the form a + bj, where a is the real part and bj is
            the imaginary part.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cmplx1 = 2 + 4j
        cmplx2 = -(3 + 7j)
        cmplx3 = -4.1j
        cmplx4 = 6j
        
        print(type(cmplx1))
        print(type(cmplx2))
        print(type(cmplx3))
        print(type(cmplx4))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        &lt;class 'complex'&gt;
        &lt;class 'complex'&gt;
        &lt;class 'complex'&gt;
        &lt;class 'complex'&gt;
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div8" style="display: none">
          <h2>Data Conversion</h2>
          <br />
          <li>
            The process of converting numeric data from one type to another is
            called as type conversion.
          </li>
          <li>To convert from integer to float, we use float() function.</li>
          <br />
          <p>
            To convert from integer to complex, we use the complex() function.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        num1 = -25
        num2 = float(num1)
        num3 = complex(num1)
        
        print(num2)
        print(num3)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        -25.0
        (-25+0j)
    </code>
    </pre>
          <br />
          <br />
          <li>
            To convert from float to integer, we use int() function. int()
            function rounds of the given number to the nearest integer value.
          </li>
          <br />
          <p>
            To convert from float to complex, we use the complex() function.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        num1 = 8.4
        num2 = int(num1)
        num3 = complex(num1)
        
        print(num2)
        print(num3)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        8
        (8.4+0j)
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>Note:</b>complex numbers cannot be converted to integer or
            float.
          </p>
          <br />
          <br />
        </div>
        <div class="notes" id="div9" style="display: none">
          <h2>Type Casting</h2>
          <br />
          <p>
            Similar to type conversion, type casting is done when we want to
            specify a type on a variable.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "7"          
        str2 = "3.142"
        str3 = "13"
        num1 = 29
        num2 = 6.67
        
        print(int(str1))
        print(float(str2))
        print(float(str3))
        print(str(num1))
        print(str(num2))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        7
        3.142
        13.0
        29
        6.67
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div10" style="display: none">
          <h2>Python Operators</h2>
          <br />
          <p>
            Python has different types of operators for different operations.
            They are as follows:
          </p>
          <br />
          <br />
          <h3>Arithmetic operators:</h3>
          <br />
          <p>
            Arithmetic operators are used to perform arithmetic/mathematical
            operations.
          </p>
          <br />
          <table>
            <tr>
              <th>Name</th>
              <th>Operator</th>
              <th>Example</th>
            </tr>
            <tr>
              <td>Addition</td>
              <td>+</td>
              <td>a+b</td>
            </tr>
            <tr>
              <td>Subtraction</td>
              <td>-</td>
              <td>a-b</td>
            </tr>
            <tr>
              <td>Multiplication</td>
              <td>*</td>
              <td>a*b</td>
            </tr>
            <tr>
              <td>Division</td>
              <td>/</td>
              <td>a/b</td>
            </tr>
            <tr>
              <td>Exponential</td>
              <td>**</td>
              <td>a**b</td>
            </tr>
            <tr>
              <td>Modulus</td>
              <td>%</td>
              <td>a%b</td>
            </tr>
            <tr>
              <td>Floor Division</td>
              <td>//</td>
              <td>a//b</td>
            </tr>
          </table>
          <br />
          <br />
          <h3>Assignment Operators:</h3>
          <br />
          <p>These operators are used to assign values to variables.</p>
          <br />
          <table>
            <tr>
              <th>Name</th>
              <th>Evaluted As</th>
            </tr>
            <tr>
              <td>=</td>
              <td>a=b</td>
            </tr>
            <tr>
              <td>+=</td>
              <td>a+=b or a=a+b</td>
            </tr>
            <tr>
              <td>-=</td>
              <td>a-=b or a=a-b</td>
            </tr>
            <tr>
              <td>*=</td>
              <td>a*=b or a=a*b</td>
            </tr>
            <tr>
              <td>**=</td>
              <td>a**=b or a=a**b</td>
            </tr>
            <tr>
              <td>/=</td>
              <td>a/=b or a=a/b</td>
            </tr>
            <tr>
              <td>//=</td>
              <td>a//=b or a=a//b</td>
            </tr>
            <tr>
              <td>%=</td>
              <td>a%=b or a=a%b</td>
            </tr>
            <tr>
              <td>&=</td>
              <td>a&=b or a=a&b</td>
            </tr>
            <tr>
              <td>|=</td>
              <td>a|=b or a=a|b</td>
            </tr>
            <tr>
              <td>^=</td>
              <td>a^=b or a=a^b</td>
            </tr>
            <tr>
              <td>>>=</td>
              <td>a>>=b or a=a>>b</td>
            </tr>
            <tr>
              <td>&lt;&lt;=</td>
              <td>a&lt;&lt;=b or a=a&lt;&lt;b</td>
            </tr>
          </table>
          <br />
          <br />
          <h3>Bitwise Operators:</h3>
          <br />
          <p>Bitwise operators are used to deal with binary operations.</p>
          <br />
          <table>
            <tr>
              <th>Name</th>
              <th>Operator</th>
              <th>Example</th>
            </tr>
            <tr>
              <td>Bitwise AND</td>
              <td>Bitwise AND</td>
              <td>a & b</td>
            </tr>
            <tr>
              <td>Bitwise OR</td>
              <td>Bitwise OR</td>
              <td>a | b</td>
            </tr>
            <tr>
              <td>Bitwise NOT</td>
              <td>Bitwise NOT</td>
              <td>~a</td>
            </tr>
            <tr>
              <td>Bitwise XOR</td>
              <td>Bitwise XOR</td>
              <td>a ^ b</td>
            </tr>
            <tr>
              <td>Bitwise right shift</td>
              <td>Bitwise right shift</td>
              <td>a>></td>
            </tr>
            <tr>
              <td>Bitwise left shift</td>
              <td>Bitwise left shift</td>
              <td>b&lt;&lt;</td>
            </tr>
          </table>
          <br />
          <br />
          <h3>Comparison Operators:</h3>
          <br />
          <p>These operators are used to compare values.</p>
          <br />
          <table>
            <tr>
              <th>Name</th>
              <th>Operator</th>
              <th>Example</th>
            </tr>
            <tr>
              <td>Equal</td>
              <td>==</td>
              <td>a==b</td>
            </tr>
            <tr>
              <td>Not Equal</td>
              <td>!=</td>
              <td>a!=b</td>
            </tr>
            <tr>
              <td>Less than</td>
              <td>&lt;</td>
              <td>a&lt;b</td>
            </tr>
            <tr>
              <td>Greater than</td>
              <td>&gt;</td>
              <td>a&gt;b</td>
            </tr>
            <tr>
              <td>Less than or Equal to</td>
              <td>&lt;=</td>
              <td>a&lt;=b</td>
            </tr>
            <tr>
              <td>Greater than or Equal to</td>
              <td>&gt;=</td>
              <td>a&gt;=b</td>
            </tr>
          </table>
          <br />
          <br />
          <h3>Identity Operators:</h3>
          <br />
          <table>
            <tr>
              <th>Name</th>
              <th>Example</th>
              <th>Evaluated As</th>
            </tr>
            <tr>
              <td>is</td>
              <td>a is b</td>
              <td>Returns True if a and b are same</td>
            </tr>
            <tr>
              <td>is not</td>
              <td>a is not b</td>
              <td>Returns True if a and b are not same</td>
            </tr>
          </table>
          <br />
          <br />
          <h3>Logical Operators:</h3>
          <br />
          <p>These operators are used to deal with logical operations.</p>
          <br />
          <table>
            <tr>
              <th>Name</th>
              <th>Operator</th>
              <th>Example</th>
            </tr>
            <tr>
              <td>AND</td>
              <td>and</td>
              <td>a=2 and b=3</td>
            </tr>
            <tr>
              <td>OR</td>
              <td>or</td>
              <td>a=2 or b=3</td>
            </tr>
            <tr>
              <td>NOT</td>
              <td>not</td>
              <td>Not(a=2 and b=3)</td>
            </tr>
          </table>
          <br />
          <br />
          <h3>Membership Operators:</h3>
          <br />
          <table>
            <tr>
              <th>Name</th>
              <th>Example</th>
              <th>Evaluated As</th>
            </tr>
            <tr>
              <td>in</td>
              <td>a in b</td>
              <td>
                Returns True if a is present in given sequence or collection
              </td>
            </tr>
            <tr>
              <td>not in</td>
              <td>a not in b</td>
              <td>
                Returns True if a is not present in given sequence or
                collection
              </td>
            </tr>
          </table>
          <br />
          <br />
          <h3>Operator Precedence in Python:</h3>
          <br />
          <table>
            <tr>
              <th>Name</th>
              <th>Operator</th>
            </tr>
            <tr>
              <td>Parenthesis</td>
              <td>()</td>
            </tr>
            <tr>
              <td>Exponential</td>
              <td>**</td>
            </tr>
            <tr>
              <td>Complement, unary plus, unary minus</td>
              <td>~ , +, -</td>
            </tr>
            <tr>
              <td>Multiply, divide, modulus, floor division</td>
              <td>*, /, %, //</td>
            </tr>
            <tr>
              <td>Addition, subtraction</td>
              <td>+, -</td>
            </tr>
            <tr>
              <td>Left shift and right shift operators</td>
              <td>&lt;&lt;, &gt;&gt;</td>
            </tr>
            <tr>
              <td>Bitwise and</td>
              <td>&</td>
            </tr>
            <tr>
              <td>Bitwise or and xor</td>
              <td>^, |</td>
            </tr>
            <tr>
              <td>Comparison Operators</td>
              <td>&lt;, &gt;, &gt;=, &lt;=</td>
            </tr>
            <tr>
              <td>Equality Operators</td>
              <td>==, !=</td>
            </tr>
            <tr>
              <td>Assignment Operators</td>
              <td>=, %=, /=, //=, -=, +=, *=, **=</td>
            </tr>
            <tr>
              <td>Identity Operators</td>
              <td>is, is not</td>
            </tr>
            <tr>
              <td>Membership Operators</td>
              <td>in, not in</td>
            </tr>
            <tr>
              <td>Logical Operators</td>
              <td>and, or, not</td>
            </tr>
          </table>
          <br />
          <br />
        </div>
        <div class="notes" id="div11" style="display: none">
          <h2>Python Booleans</h2>
          <br />
          <p>Boolean consists of only two values; True and False.</p>
          <br />
          <br />
          <h3>Why are Boolean’s needed?</h3>
          <br />
          <p>Consider the following if-else statement:</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        x = 13
        if(x>13):
            print("X is a prime number.")
        else:
            print("X is not a prime number.")
    </code>
    </pre>
          <br />
          <br />
          <h3>Is it True that X is greater than 13 or is it False?</h3>
          <br />
          <br />
          <li>
            Thus Booleans are used to know whether the given expression is
            True or False.
          </li>
          <li>
            <b>bool() function</b>evaluates values and returns True or False.
          </li>
          <br /><br />
          <p>
            Here are some examples where the Boolean returns True/False values
            for different datatypes.
          </p>
          <br />
          <h3>None:</h3>
          <br />
          <pre class="highlight">
    <code class="language-js">
        print("None: ",bool(None))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        None:  False
    </code>
    </pre>
          <br />
          <br />
          <h3>Numbers:</h3>
          <br />
          <pre class="highlight">
    <code class="language-js">
        print("Zero:",bool(0))
        print("Integer:",bool(23))
        print("Float:",bool(3.142))
        print("Complex:",bool(5+2j)) 
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Zero: False
        Integer: True
        Float: True
        Complex: True
    </code>
    </pre>
          <br />
          <br />
          <h3>Strings:</h3>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #Strings
        print("Any string:",bool("Nilesh"))   
        print("A string containing number:",bool("8.5"))      
        print("Empty string:" ,"")   
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Any string: True
        A string containing number: True
        Empty string: False
    </code>
    </pre>
          <br />
          <br />
          <h3>Lists:</h3>
          <br />
          <pre class="highlight">
    <code class="language-js">
        print("Empty List:",bool([]))
        print("List:",bool([1,2,5,2,1,3]))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Empty List: False
        List: True
    </code>
    </pre>
          <br />
          <br />
          <h3>Tuples:</h3>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #Tuples
        print("Empty Tuple:",bool(()))
        print("Tuple:",bool(("Horse", "Rhino", "Tiger")))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Empty Tuple: False
        Tuple: True
    </code>
    </pre>
          <br />
          <br />
          <h3>Sets and Dictionaries:</h3>
          <br />
          <pre class="highlight">
    <code class="language-js">
        print("Empty Dictionary:",bool({}))
        print("Empty Set:",bool({"Mike", 22, "Science"}))
        print("Dictionary:",bool({"name":"Lakshmi", "age":24 ,"job":"unemployed"}))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Empty Dictionary: False
        Empty Set: True
        Dictionary: True
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div12" style="display: none">
          <h2>Python Strings</h2>
          <br />
          <h3>What are strings?</h3>
          <br />
          <p>
            In python, anything that you enclose between single or double
            quotation marks is considered a string. A string is essentially a
            sequence or array of textual data.
            <br />
            Strings are used when working with Unicode characters.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        name = "Laddu"
        print("Hello, " + name)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello, Laddu
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>Note:</b>It does not matter whether you enclose your strings in
            single or double quotes, the output remains the same.
          </p>
          <br />
          <br />
          <p>
            Sometimes, the user might need to put quotation marks in between
            the strings. Example, consider the sentence: He said, “I want to
            eat an apple”.
            <br />
            How will you print this statement in python?
          </p>
          <br />
          <br />
          <color>Wrong way X</color><br />
          <pre class="highlight">
    <code class="language-js">
        print("He said, "I want to eat an apple".")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
print("He said, "I want to eat an apple".")
        ^
SyntaxError: invalid syntax
    </code>
    </pre>
          <br />
          <br />
          <color>Right way </color><br />
          <pre class="highlight">
    <code class="language-js">
        print('He said, "I want to eat an apple".')
        #OR
        print("He said, \"I want to eat an apple\".")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        He said, "I want to eat an apple".
        He said, "I want to eat an apple".
    </code>
    </pre>
          <br />
          <br />
          <h3>What if you want to write multiline strings?</h3>
          <br />
          <p>
            Sometimes the programmer might want to include a note, or a set of
            instructions, or just might want to explain a piece of code.
            Although this might be done using multiline comments, the
            programmer may want to display this in the execution of
            programmer. This is done using multiline strings.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        receipe = """
        1. Heat the pan and add oil
        2. Crack the egg
        3. Add salt in egg and mix well
        4. Pour the mixture in pan
        5. Fry on medium heat
        """
        print(receipe)
        
        note = '''
        This is a multiline string
        It is used to display multiline message in the program
        '''
        print(note)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        1. Heat the pan and add oil
        2. Crack the egg
        3. Add salt in egg and mix well
        4. Pour the mixture in pan
        5. Fry on medium heat


        This is a multiline string
        It is used to display multiline message in the program
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div13" style="display: none">
          <h2>Operation on Strings</h2>
          <br />
          <h3>Length of a String:</h3>
          <br />
          <p>We can find the length of a string using len() function.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        fruit = "Mango"
        len1 = len(fruit)
        print("Mango is a", len1, "letter word.")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Mango is a 5 letter word. 
    </code>
    </pre>
          <br />
          <br />
          <h3>String as an Array:</h3>
          <br />
          <p>
            A string is essentially a sequence of characters also called an
            array. Thus we can access the elements of this array.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        pie = "ApplePie"
        print(pie[:5])
        print(pie[6])	#returns character at specified index
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Apple
        i
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>Note:</b>This method of specifying the start and end index to
            specify a part of a string is called slicing.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        pie = "ApplePie"
        print(pie[:5])      #Slicing from Start
        print(pie[5:])      #Slicing till End
        print(pie[2:6])     #Slicing in between
        print(pie[-8:])     #Slicing using negative index
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Apple
        Pie
        pleP
        ApplePie
    </code>
    </pre>
          <br />
          <br />
          <h3>Loop through a String:</h3>
          <br />
          <p>
            Strings are arrays and arrays are iterable. Thus we can loop
            through strings.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        alphabets = "ABCDE"
        for i in alphabets:
            print(i)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        A
        B
        C
        D
        E  
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div14" style="display: none">
          <h2>String Methods</h2>
          <br />
          <p>
            Python provides a set of built-in methods that we can use to alter
            and modify the strings.
          </p>
          <br />
          <br />
          <h3>
            upper() : The upper() method converts a string to upper case.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "AbcDEfghIJ"
        print(str1.upper())
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
       ABCDFGHIJ
    </code>
    </pre>
          <br />
          <br />
          <h3>
            lower() : The lower() method converts a string to upper case.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "AbcDEfghIJ"
        print(str1.upper())
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
       abcdefghij
    </code>
    </pre>
          <br />
          <br />
          <h3>
            strip() : The strip() method removes any white spaces before and
            after the string.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str2 = " Silver Spoon "
        print(str2.strip)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Silver Spoon
    </code>
    </pre>
          <br />
          <br />
          <h3>rstrip() : the rstrip() removes any trailing characters.</h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str3 = "Hello !!!"
        print(str3.rstrip("!"))
    </code>    
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello
    </code>
    </pre>
          <br />
          <br />
          <h3>
            replace() : the replace() method replaces a string with another
            string.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str2 = "Silver Spoon"
        print(str2.replace("Sp", "M"))
    </code>    
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Silver Moon
    </code>
    </pre>
          <br />
          <br />
          <h3>
            split() : The split() method splits the give string at the
            specified instance and returns the separated strings as list
            items.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str2 = "Silver Spoon"
        print(str2.split(" "))      #Splits the string at the whitespace " ".
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Silver', 'Spoon']
    </code>
    </pre>
          <br />
          <br />
          <p>
            There are various other string methods that we can use to modify
            our strings.
          </p>
          <br />
          <br />
          <h3>
            capitalize() : The capitalize() method turns only the first
            character of the string to uppercase and the rest other characters
            of the string are turned to lowercase. The string has no effect if
            the first character is already uppercase.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "hello"
        capStr1 = str1.capitalize()
        print(capStr1)
        str2 = "hello WorlD"
        capStr2 = str2.capitalize()
        print(capStr2)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello
        Hello world
    </code>
    </pre>
          <br />
          <br />
          <h3>
            center() : The center() method aligns the string to the center as
            per the parameters given by the user.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Welcome to the Console!!!"
        print(str1.center(50))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Welcome to the Console!!!
    </code>
    </pre>
          <br />
          <br />
          <p>
            We can also provide padding character. It will fill the rest of
            the fill characters provided by the user.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Welcome to the Console!!!"
        print(str1.center(50, "."))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ............Welcome to the Console!!!.............
    </code>
    </pre>
          <br />
          <br />
          <h3>
            count() : The count() method returns the number of times the given
            value has occurred within the given string.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str2 = "Abracadabra"
        countStr = str2.count("a")
        print(countStr)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        4
    </code>
    </pre>
          <br />
          <br />
          <h3>
            endswith() : The endswith() method checks if the string ends with
            a given value. If yes then return True, else return False.
          </h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Welcome to the Console !!!"
        print(str1.endswith("!!!"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
       True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Welcome to the Console !!!"
        print(str1.endswith("Console"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
       False
    </code>
    </pre>
          <br />
          <br />
          <p>
            We can even also check for a value in-between the string by
            providing start and end index positions.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Welcome to the Console !!!"
        print(str1.endswith("to", 4, 10))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
       True
    </code>
    </pre>
          <br />
          <br />
          <h3>
            find() : The find() method searches for the first occurrence of
            the given value and returns the index where it is present. If
            given value is absent from the string then return -1.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "He's name is Dan. He is an honest man."
        print(str1.find("is"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
       19
    </code>
    </pre>
          <br />
          <br />
          <p>
            As we can see, this method is somewhat similar to the index()
            method. The major difference being that index() raises an
            exception if value is absent whereas find() does not.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "He's name is Dan. He is an honest man."
        print(str1.find("Daniel"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
      -1
    </code>
    </pre>
          <br />
          <br />
          <h3>
            index() : The index() method searches for the first occurrence of
            the given value and returns the index where it is present. If
            given value is absent from the string then raise an exception.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "He's name is Dan. Dan is an honest man."
        print(str1.find("Dan"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
      13
    </code>
    </pre>
          <br />
          <br />
          <p>
            As we can see, this method is somewhat similar to the find()
            method. The major difference being that index() raises an
            exception if value is absent whereas find() does not.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "He's name is Dan. Dan is an honest man."
        print(str1.index("Daniel"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ValueError: substring not found
    </code>
    </pre>
          <br />
          <br />
          <h3>
            isalnum() : The isalnum() method returns True only if the entire
            string only consists of A-Z, a-z, 0-9. If any other characters or
            punctuations are present, then it returns False.
          </h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "WelcomeToTheConsole"
        print(str1.isalnum())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1= "Welcome to The Console"
        print(str1.isalnum())
        str2 = "Nation!!!"
        print(str2.isalnum())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
        False
    </code>
    </pre>
          <br />
          <br />
          <h3>
            isalpha() : The isalnum() method returns True only if the entire
            string only consists of A-Z, a-z. If any other characters or
            punctuations or numbers(0-9) are present, then it returns False.
          </h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Welcome"
        print(str1.isalpha())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        tr1 = "I'm 18 years old"
        print(str1.isalpha())
        str2 = "Coding!!!"
        print(str2.isalnum())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
        False
    </code>
    </pre>
          <br />
          <br />
          <h3>
            islower() : The islower() method returns True if all the
            characters in the string are lower case, else it returns False.
          </h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "hello world"
        print(str1.islower())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "welcome Mike"
        print(str1.islower())
        str2 = "Coding!!!"
        print(str2.islower())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
        False
    </code>
    </pre>
          <br />
          <br />
          <h3>
            isprintable() : The isprintable() method returns True if all the
            values within the given string are printable, if not, then return
            False.
          </h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "We wish you a Merry Christmas"
        print(str1.isprintable())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str2 = "Hello, \t\t.Mike"
        print(str2.isprintable())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
    </code>
    </pre>
          <br />
          <br />
          <h3>
            isspace() : The isspace() method returns True only and only if the
            string contains white spaces, else returns False.
          </h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "        "       #using Spacebar
        print(str1.isspace())
        str2 = "        "       #using Tab
        print(str2.isspace())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
        True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Hello World" 
        print(str1.isspace())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
    </code>
    </pre>
          <br />
          <br />
          <h3>
            istitle() : The istitile() returns True only if the first letter
            of each word of the string is capitalized, else it returns False.
          </h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "World Health Organization" 
        print(str1.istitle())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str2 = "To kill a Mocking bird"
        print(str2.istitle())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
    </code>
    </pre>
          <br />
          <br />
          <h3>
            isupper() : The isupper() method returns True if all the
            characters in the string are upper case, else it returns False.
          </h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "WORLD HEALTH ORGANIZATION" 
        print(str1.isupper())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str2 = "To kill a Mocking bird"
        print(str2.isupper())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
    </code>
    </pre>
          <br />
          <br />
          <h3>
            replace() : The replace() method can be used to replace a part of
            the original string with another string.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Python is a Compiled Language." 
        print(str1.replace("Compiled", "Interpreted"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Python is a Interpreted Language.
    </code>
    </pre>
          <br />
          <br />
          <h3>
            startswith() : The endswith() method checks if the string starts
            with a given value. If yes then return True, else return False.
          </h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Python is a Interpreted Language" 
        print(str1.startswith("Python"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Python is a Interpreted Language" 
        print(str1.startswith("a"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
    </code>
    </pre>
          <br />
          <br />
          <p>
            We can even also check for a value in-between the string by
            providing start and end index positions.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Python is a Interpreted Language" 
        print(str1.startswith("Inter", 12, 20)) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h3>
            swapcase() : The swapcase() method changes the character casing of
            the string. Upper case are converted to lower case and lower case
            to upper case.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "Python is a Interpreted Language" 
        print(str1.swapcase())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        PYTHON IS A INTERPRETED LANGUAGE
    </code>
    </pre>
          <br />
          <br />
          <h3>
            title() : The title() method capitalizes each letter of the word
            within the string.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "He's name is Dan. Dan is an honest man."
        print(str1.title())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        He'S Name Is Dan. Dan Is An Honest Man. 
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div15" style="display: none">
          <h2>Format Strings</h2>
          <br />
          <h3>What if we want to join two separated strings?</h3>
          <br />
          <p>
            We can perform concatenation to join two or more separate strings.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str4 = "Captain"
        str5 = "America"
        str6 = str4 + " " + str5
        print(str6)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Captain America
    </code>
    </pre>
          <br />
          <br />
          <p>
            In the above example, we saw how one can concatenate two strings.
            But how can we concatenate a string and an integer?
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        name = "Chintha"
        age = 18
        print("My name is" + name + "and my age is" + age)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        TypeError: can only concatenate str (not "int") to str
    </code>
    </pre>
          <br />
          <br />
          <p>
            As we can see, we cannot concatenate a string to another data
            type.
          </p>
          <br />
          <h3>So what’s the solution?</h3>
          <br />
          <p>
            We make the use of format() method. The format() methods places
            the arguments within the string wherever the placeholders are
            specified.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        name = "Guzman"
        age = 18
        statement = "My name is {} and my age is {}."
        print(statement.format(name, age)) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        My name is Guzman and my age is 18.
    </code>
    </pre>
          <br />
          <br />
          <p>
            We can also make the use of indexes to place the arguments in
            specified order.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        quantity = 2
        fruit = "Apples"
        cost = 120.0
        statement = "I want to buy {2} dozen {0} for {1}$"
        print(statement.format(fruit,cost,quantity))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        I want to buy 2 dozen Apples for $120.0
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div16" style="display: none">
          <h2>Escape characters</h2>
          <br />
          <p>
            Escape Characters are very important in python. It allows us to
            insert illegal characters into a string like a back slash, new
            line or a tab.
            <br />
            Single/Double Quote: used to insert single/double quotes in the
            string.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "He was \"Flabergasted\"."
        str2 = 'He was \'Flabergasted\'.'
        print(str1)
        print(str2)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        He was "Flabergasted".
        He was 'Flabergasted'.
    </code>
    </pre>
          <br />
          <br />
          <h3>New Line: inserts a new line wherever specified.</h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str1 = "I love doing Yoga. \nIt cleanses my mind and my body."
        print(str1)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        I love doing Yoga.
        It cleanses my mind and my body.
    </code>
    </pre>
          <br />
          <br />
          <h3>Tab: inserts a tab wherever specified.</h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str2 = "Hello \t\tWorld \t!!!"
        print(str2)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello           World   !!!
    </code>
    </pre>
          <br />
          <br />
          <h3>
            Backspace: erases the character before it wherever it is
            specified.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str2 = "Hello  \bWorld !!!"
        print(str2)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello World   !!!
    </code>
    </pre>
          <br />
          <br />
          <h3>Backslash: used to insert a backslash into a string.</h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        str3 = "What will you eat? Apple\\Banana"
        print(str3)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        What will you eat? Apple\Banana
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div17" style="display: none">
          <h2>Python Lists</h2>
          <br />
          <li>Lists are ordered collection of data items.</li>
          <li>They store multiple items in a single variable.</li>
          <li>
            List items are separated by commas and enclosed within square
            brackets [].
          </li>
          <li>
            Lists are changeable meaning we can alter them after creation.
          </li>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        lst1 = [1,2,2,3,5,4,6]
        lst2 = ["Red", "Green", "Blue"]
        print(lst1)
        print(lst2)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        [1, 2, 2, 3, 5, 4, 6]
        ['Red', 'Green', 'Blue']
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        details = ["Abhijeet", 18, "FYBScIT", 9.8]
        print(details)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
         ['Abhijeet', 18, 'FYBScIT', 9.8]
    </code>
    </pre>
          <br />
          <br />
          <p>
            As we can see, a single list can contain items of different
            datatypes.
          </p>
          <br />
          <br />
        </div>
        <div class="notes" id="div18" style="display: none">
          <h2>List Indexes</h2>
          <br />
          <p>
            Each item/element in a list has its own unique index. This index
            can be used to access any particular item from the list. The first
            item has index [0], second item has index [1], third item has
            index [2] and so on.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["Red", "Green", "Blue", "Yellow", "Green"]
        #          [0]      [1]     [2]      [3]      [4]
    </code>   
    </pre>
          <br />
          <br />
          <h3>Accessing list items:</h3>
          <br />
          <br />
          <h3>Positive Indexing:</h3>
          <br />
          <p>
            As we have seen that list items have index, as such we can access
            items using these indexes.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["Red", "Green", "Blue", "Yellow", "Green"]
        #          [0]      [1]     [2]      [3]      [4]
        print(colors[2])
        print(colors[4])
        print(colors[0])
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Blue
        Green
        Red  
    </code>
    </pre>
          <br />
          <br />
          <h3>Negative Indexing:</h3>
          <br />
          <p>
            Similar to positive indexing, negative indexing is also used to
            access items, but from the end of the list. The last item has
            index [-1], second last item has index [-2], third last item has
            index [-3] and so on.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["Red", "Green", "Blue", "Yellow", "Green"]
        #          [-5]    [-4]    [-3]     [-2]      [-1]
        print(colors[-1])
        print(colors[-3])
        print(colors[-5])
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Green
        Blue
        Red  
    </code>
    </pre>
          <br />
          <br />
          <h3>Check for item:</h3>
          <br />
          <p>
            We can check if a given item is present in the list. This is done
            using the in keyword.
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["Red", "Green", "Blue", "Yellow", "Green"]
        if "Yellow" in colors:
            print("Yellow is present.")
        else:
            print("Yellow is absent.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Yellow is present.
    </code>
    </pre>
          <br />
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["Red", "Green", "Blue", "Yellow", "Green"]
        if "Orange" in colors:
            print("Orange is present.")
        else:
            print("Orange is absent.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Orange is absent.
    </code>
    </pre>
          <br />
          <br />
          <h3>Range of Index:</h3>
          <br />
          <p>
            You can print a range of list items by specifying where do you
            want to start, where do you want to end and if you want to skip
            elements in between the range.
          </p>
          <br />
          <h3>Syntax:</h3>
          <br />
          <p>
            List[start : end : jumpIndex]
            <br />
            Note: jump Index is optional. We will see this in given examples.
          </p>
          <br />
          <br />
          <p><b>Example:</b>printing elements within a particular range:</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ["cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow"]
        print(animals[3:7])	#using positive indexes
        print(animals[-7:-2])	#using negative indexes 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['mouse', 'pig', 'horse', 'donkey']
        ['bat', 'mouse', 'pig', 'horse', 'donkey']
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here, we provide index of the element from where we want to start
            and the index of the element till which we want to print the
            values.
          </p>
          <br />
          <p>
            <b>Note:</b>The element of the end index provided will not be
            included.
          </p>
          <br />
          <p>
            <b>Example:</b> printing all element from a given index till the
            end
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ["cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow"]
        print(animals[4:])	#using positive indexes
        print(animals[-4:])	#using negative indexes 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['pig', 'horse', 'donkey', 'goat', 'cow']
        ['horse', 'donkey', 'goat', 'cow']
    </code>
    </pre>
          <br />
          <br />
          <p>
            When no end index is provided, the interpreter prints all the
            values till the end.
          </p>
          <br /><br />
          <p>
            <b>Example:</b> printing all elements from start to a given index
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ["cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow"]
        print(animals[:6])	#using positive indexes
        print(animals[:-3])	#using negative indexes 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['cat', 'dog', 'bat', 'mouse', 'pig', 'horse']
        ['cat', 'dog', 'bat', 'mouse', 'pig', 'horse']
    </code>
    </pre>
          <br />
          <br />
          <p>
            When no start index is provided, the interpreter prints all the
            values from start up to the end index provided.
          </p>
          <br />
          <p><b>Example:</b> print alternate values</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ["cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow"]
        print(animals[::2])	#using positive indexes
        print(animals[-8:-1:2])	#using negative indexes 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['cat', 'bat', 'pig', 'donkey', 'cow']
        ['dog', 'mouse', 'horse', 'goat']
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here, we have not provided start and index, which means all the
            values will be considered. But as we have provided a jump index of
            2 only alternate values will be printed.
          </p>
          <br />
          <br />
          <p>
            <b>Example:</b>printing every 3rd consecutive withing given range
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ["cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow"]
        print(animals[1:8:3])    
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['dog', 'pig', 'goat']   
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here, jump index is 3. Hence it prints every 3rd element within
            given index.
          </p>
          <br />
          <br />
        </div>
        <div class="notes" id="div19" style="display: none">
          <h2>Add List Items</h2>
          <br />
          <p>
            There are three methods to add items to list: append(), insert()
            and extend()
          </p>
          <br />
          <h3>append():</h3>
          <br />
          <p>This method appends items to the end of the existing list.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue"]
        colors.append("green")
        print(colors)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['voilet', 'indigo', 'blue', 'green'] 
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>What if you want to insert an item in the middle of the list?
              At a specific index?</b>
          </p>
          <br />
          <br />
          <h3>insert():</h3>
          <br />
          <p>
            This method inserts an item at the given index. User has to
            specify index and the item to be inserted within the insert()
            method.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue"]
        #           [0]        [1]      [2]
        
        colors.insert(1, "green")   #inserts item at index 1
        # updated list: colors = ["voilet", "green", "indigo", "blue"]
        #       indexs              [0]       [1]       [2]      [3]
        
        print(colors) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['voilet', 'green', 'indigo', 'blue'] 
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>What if you want to append an entire list or any other
              collection (set, tuple, dictionary) to the existing list?</b>
          </p>
          <br />
          <h3>extend():</h3>
          <br />
          <p>
            This method adds an entire list or any other collection datatype
            (set, tuple, dictionary) to the existing list.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #add a list to a list
        colors = ["voilet", "indigo", "blue"]
        rainbow = ["green", "yellow", "orange", "red"]
        colors.extend(rainbow)
        print(colors)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['voilet', 'indigo', 'blue', 'green', 'yellow', 'orange', 'red']
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #add a tuple to a list
        cars = ["Hyundai", "Tata", "Mahindra"]
        cars2 = ("Mercedes", "Volkswagen", "BMW")
        cars.extend(cars2)
        print(cars)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Hyundai', 'Tata', 'Mahindra', 'Mercedes', 'Volkswagen', 'BMW']
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 3:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #add a set to a list
        cars = ["Hyundai", "Tata", "Mahindra"]
        cars2 = {"Mercedes", "Volkswagen", "BMW"}
        cars.extend(cars2)
        print(cars)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Hyundai', 'Tata', 'Mahindra', 'Mercedes', 'BMW', 'Volkswagen']
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 4:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        #add a dictionary to a list
        students = ["Sakshi", "Aaditya", "Ritika"]
        students2 = {"Yash":18, "Devika":19, "Soham":19}    #only add keys, does not add values
        students.extend(students2)
        print(students)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Sakshi', 'Aaditya', 'Ritika', 'Yash', 'Devika', 'Soham']
    </code>
    </pre>
          <br />
          <br />
          <h3>Concatenate two lists:</h3>
          <br />
          <p>you can simply concatenate two list to join two lists.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue", "green"]
        colors2 = ["yellow", "orange", "red"]
        print(colors + colors2)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['voilet', 'indigo', 'blue', 'green', 'yellow', 'orange', 'red']
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div20" style="display: none">
          <h2>Remove List Items</h2>
          <br />
          <p>
            There are various methods to remove items from the list: pop(),
            remove(), del(), clear()
          </p>
          <br />
          <br />
          <h3>pop():</h3>
          <br />
          <p>
            This method removes the last item of the list if no index is
            provided. If an index is provided, then it removes item at that
            specified index.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["Red", "Green", "Blue", "Yellow", "Green"]
colors.pop()        #removes the last item of the list
print(colors)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Red', 'Green', 'Blue', 'Yellow']
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["Red", "Green", "Blue", "Yellow", "Green"]
        colors.pop(1)       #removes item at index 1
        print(colors)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Red', 'Blue', 'Yellow', 'Green']
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>What if you want to remove a specific item from the list?</b>
          </p>
          <br />
          <h3>remove():</h3>
          <br />
          <p>This method removes specific item from the list.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue", "green", "yellow"]
        colors.remove("blue")
        print(colors)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['voilet', 'indigo', 'green', 'yellow']
    </code>
    </pre>
          <br />
          <br />
          <h3>del():</h3>
          <br />
          <p>
            del is not a method, rather it is a keyword which deletes item at
            specific from the list, or deletes the list entirely.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue", "green", "yellow"]
        del colors[3]
        print(colors)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['voilet', 'indigo', 'blue', 'yellow']
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue", "green", "yellow"]
        del colors
        print(colors)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        NameError: name 'colors' is not defined
    </code>
    </pre>
          <br />
          <br />
          <p>
            We get an error because our entire list has been deleted and there
            is no variable called colors which contains a list.
          </p>
          <br />
          <p>
            <b>What if we don’t want to delete the entire list, we just want
              to delete all items within that list?</b>
          </p>
          <br />
          <br />
          <h3>clear():</h3>
          <br />
          <p>
            This method clears all items in the list and prints an empty list.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue", "green", "yellow"]
        colors.clear()
        print(colors)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        []
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div21" style="display: none">
          <h2>Change List Items</h2>
          <br />
          <p>
            Changing items from list is easier, you just have to specify the
            index where you want to replace the item with existing item.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        names = ["Jeeva", "Sarah", "Nadia", "Oleg", "Steve"]
        names[2] = "Millie"
        print(names)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Jeeva', 'Sarah', 'Millie', 'Oleg', 'Steve']
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>You can also change more than a single item at once. </b>To do
            this, just specify the index range over which you want to change
            the items.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        names = ["Jeeva", "Sarah", "Nadia", "Oleg", "Steve"]
        names[2:4] = ["junnu", "Anastasia"]
        print(names)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Jeeva', 'Sarah', 'Junnu', 'Anastasia', 'Steve']
    </code>
    </pre>
          <br />
          <br />
          <b>What if the range of the index is more than the list of items
            provided?</b>
          <br />
          <p>
            In this case, all the items within the index range of the original
            list are replaced by the items that are provided.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        names = ["Jeeva", "Sarah", "Nadia", "Oleg", "Steve"]
        names[1:4] = ["junnu", "Anastasia"]
        print(names)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Jeeva', 'junnu' 'Anastasia', 'Steve']
    </code>
    </pre>
          <br />
          <br />
          <b>What if we have more items to be replaced than the index range
            provided?</b><br />
          <p>
            In this case, the original items within the range are replaced by
            the new items and the remaining items move to the right of the
            list accordingly.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        names = ["Jeeva", "Sarah", "Nadia", "Oleg", "Steve"]
        names[2:3] = ["junnu", "Anastasia", "Bruno", "Olga", "Rosa"]
        print(names)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Jeeva', 'sarah', junnu' 'Anastasia', 'Bruno', 'Olga', 'Rosa' 'Steve']
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div22" style="display: none">
          <h2>List Comprehension</h2>
          <br />
          <p>
            List comprehensions are used for creating new lists from other
            iterables like lists, tuples, dictionaries, sets, and even in
            arrays and strings.
          </p>
          <br />
          <h3>Syntax:</h3>
          <br />
          <p>
            List = [expression(item) for item in iterable if condition]
            <br />
            <b>expression: </b>it is the item which is being iterated.
            <br />
            <b>iterable:</b> it can be list, tuples, dictionaries, sets, and
            even in arrays and strings.
            <br />
            <b>condition:</b> condition checks if the item should be added to
            the new list or not.
          </p>
          <br />
          <br />
          <p>
            <b>Example 1:</b> accepts items with the small letter “o” in the
            new list
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        names = ["Milo", "Sarah", "Bruno", "Anastasia", "Rosa"]
        namesWith_O = [item for item in names if "o" in item]
        print(namesWith_O)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Milo', 'Bruno', 'Rosa']
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>Example 2:</b> accepts items which have more than 4 letters
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        names = ["Milo", "Sarah", "Bruno", "Anastasia", "Rosa"]
        namesWith_O = [item for item in names if (len(item) > 4)]
        print(namesWith_O)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Sarah', 'Bruno', 'Anastasia']
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div23" style="display: none">
          <h2>List Methods</h2>
          <br />
          <p>
            We have discussed methods like append(), clear(), extend(),
            insert(), pop(), remove() before. Now we will learn about some
            more list methods:
          </p>
          <br />
          <br />
          <h3>sort(): This method sorts the list in ascending order.</h3>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue", "green"]
        colors.sort()
        print(colors)

        num = [4,2,5,3,6,1,2,1,2,8,9,7]
        num.sort()
        print(num)   
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['blue', 'green', 'indigo', 'voilet']
        [1, 1, 2, 2, 2, 3, 4, 5, 6, 7, 8, 9]  
    </code>
    </pre>
          <br />
          <br />
          <h3>What if you want to print the list in descending order?</h3>
          <br />
          <p>We must give reverse=True as a parameter in the sort method.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue", "green"]
        colors.sort(reverse=True)
        print(colors)
        
        num = [4,2,5,3,6,1,2,1,2,8,9,7]
        num.sort(reverse=True)
        print(num)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['voilet', 'indigo', 'green', 'blue'] 
        [9, 8, 7, 6, 5, 4, 3, 2, 2, 2, 1, 1]
    </code>
    </pre>
          <br />
          <br />
          <p>
            The reverse parameter is set to False by default.
            <br />
            <b>Note:</b> Do not mistake the reverse parameter with the reverse
            method.
          </p>
          <br />
          <h3>reverse(): This method reverses the order of the list.</h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "indigo", "blue", "green"]
        colors.reverse()
        print(colors)
        
        num = [4,2,5,3,6,1,2,1,2,8,9,7]
        num.reverse()
        print(num)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['green', 'blue', 'indigo', 'voilet']
        [7, 9, 8, 2, 1, 2, 1, 6, 3, 5, 2, 4]
    </code>
    </pre>
          <br />
          <br />
          <h3>
            index(): This method returns the index of the first occurrence of
            the list item.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "green", "indigo", "blue", "green"]
        print(colors.index("green"))
        
        num = [4,2,5,3,6,1,2,1,3,2,8,9,7]
        print(num.index(3))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        1
        3
    </code>
    </pre>
          <br />
          <br />
          <h3>
            count(): Returns the count of the number of items with the given
            value.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "green", "indigo", "blue", "green"]
        print(colors.count("green"))
        
        num = [4,2,5,3,6,1,2,1,3,2,8,9,7]
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        2
        3
    </code>
    </pre>
          <br />
          <br />
          <h3>
            copy(): Returns copy of the list. This can be done to perform
            operations on the list without modifying the original list.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ["voilet", "green", "indigo", "blue"]
        newlist = colors.copy()
        print(colors)
        print(newlist) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['voilet', 'green', 'indigo', 'blue']
        ['voilet', 'green', 'indigo', 'blue']
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div24" style="display: none">
          <h2>Python Tuples</h2>
          <br />
          <p>
            Tuples are ordered collection of data items. They store multiple
            items in a single variable. Tuple items are separated by commas
            and enclosed within round brackets (). Tuples are unchangeable
            meaning we can not alter them after creation.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        tuple1 = (1,2,2,3,5,4,6)
        tuple2 = ("Red", "Green", "Blue")
        print(tuple1)
        print(tuple2) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        (1, 2, 2, 3, 5, 4, 6)
        ('Red', 'Green', 'Blue')
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        details = ("Abhijeet", 18, "FYBScIT", 9.8)
        print(details)  
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ('Abhijeet', 18, 'FYBScIT', 9.8)
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div25" style="display: none">
          <h2>Tuple Indexes</h2>
          <br />
          <p>
            Each item/element in a tuple has its own unique index. This index
            can be used to access any particular item from the tuple. The
            first item has index [0], second item has index [1], third item
            has index [2] and so on.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        country = ("Spain", "Italy", "India", "England", "Germany")
        #            [0]      [1]      [2]       [3]        [4]
    </code>   
    </pre>
          <br />
          <br />
          <h3>Accessing tuple items:</h3>
          <br />
          <br />
          <h3>1. Positive Indexing:</h3>
          <br />
          <p>
            As we have seen that tuple items have index, as such we can access
            items using these indexes.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        country = ("Spain", "Italy", "India", "England", "Germany")
        #            [0]      [1]      [2]       [3]        [4]
        print(country[1])
        print(country[3])
        print(country[0]) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Italy
        England
        Spain
    </code>
    </pre>
          <br />
          <br />
          <h3>2. Negative Indexing</h3>
          <br />
          <p>
            Similar to positive indexing, negative indexing is also used to
            access items, but from the end of the tuple. The last item has
            index [-1], second last item has index [-2], third last item has
            index [-3] and so on.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        country = ("Spain", "Italy", "India", "England", "Germany")
        #            [0]      [1]      [2]       [3]        [4]
        print(country[-1])
        print(country[-3])
        print(country[-4]) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Germany
        India
        Italy
    </code>
    </pre>
          <br />
          <br />
          <h3>3. Check for item:</h3>
          <br />
          <p>
            We can check if a given item is present in the tuple. This is done
            using the in keyword.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        country = ("Spain", "Italy", "India", "England", "Germany")
        if "Germany" in country:
            print("Germany is present.")
        else:
            print("Germany is absent.") 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Germany is present.
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        country = ("Spain", "Italy", "India", "England", "Germany")
if "Russia" in country:
    print("Russia is present.")
else:
    print("Russia is absent.") 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Russia is absent.  
    </code>
    </pre>
          <br />
          <br />
          <h3>4. Range of Index:</h3>
          <br />
          <p>
            You can print a range of tuple items by specifying where do you
            want to start, where do you want to end and if you want to skip
            elements in between the range.
          </p>
          <br />
          <h4>Syntax</h4>
          <br />
          <p>
            Tuple[start : end : jumpIndex]
            <br />
            <b>Note:</b> jump Index is optional. We will see this in given
            examples.
          </p>
          <br />
          <p><b>Example:</b>printing elements within a particular range:</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ("cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow")
print(animals[3:7])     #using positive indexes
print(animals[-7:-2])   #using negative indexes 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ('mouse', 'pig', 'horse', 'donkey')
        ('bat', 'mouse', 'pig', 'horse', 'donkey')
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here, we provide index of the element from where we want to start
            and the index of the element till which we want to print the
            values.
            <br />
            <b>Note:</b> The element of the end index provided will not be
            included.
          </p>
          <br />
          <p>
            <b>Example:</b> printing all element from a given index till the
            end
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ("cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow")
        print(animals[4:])      #using positive indexes
        print(animals[-4:])     #using negative indexes
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ('pig', 'horse', 'donkey', 'goat', 'cow')
        ('horse', 'donkey', 'goat', 'cow')
    </code>
    </pre>
          <br />
          <br />
          <p>
            When no end index is provided, the interpreter prints all the
            values till the end.
          </p>
          <br />
          <p>
            <b>Example:</b> printing all elements from start to a given index
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ("cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow")
        print(animals[:6])      #using positive indexes
        print(animals[:-3])     #using negative indexes
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ('cat', 'dog', 'bat', 'mouse', 'pig', 'horse')
        ('cat', 'dog', 'bat', 'mouse', 'pig', 'horse')
    </code>
    </pre>
          <br />
          <br />
          <p>
            When no start index is provided, the interpreter prints all the
            values from start up to the end index provided.
          </p>
          <br />
          <p><b>Example:</b>print alternate values</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ("cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow")
        print(animals[::2])     #using positive indexes
        print(animals[-8:-1:2]) #using negative indexes
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ('cat', 'bat', 'pig', 'donkey', 'cow')
        ('dog', 'mouse', 'horse', 'goat')
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here, we have not provided start and index, which means all the
            values will be considered. But as we have provided a jump index of
            2 only alternate values will be printed.
          </p>
          <br />
          <p>
            <b>Example:</b> printing every 3rd consecutive withing given range
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        animals = ("cat", "dog", "bat", "mouse", "pig", "horse", "donkey", "goat", "cow")
        print(animals[1:8:3]) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ('dog', 'pig', 'goat') 
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here, jump index is 3. Hence it prints every 3rd element within
            given index.
          </p>
          <br />
          <br />
        </div>
        <div class="notes" id="div26" style="display: none">
          <h2>Manipulating Tuples</h2>
          <br />
          <p>
            Tuples are immutable, hence if you want to add, remove or change
            tuple items, then first you must convert the tuple to a list. Then
            perform operation on that list and convert it back to tuple.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        countries = ("Spain", "Italy", "India", "England", "Germany")
        temp = list(countries)
        temp.append("Russia")       #add item 
        temp.pop(3)                 #remove item
        temp[2] = "Finland"         #change item
        countries = tuple(temp)
        print(countries)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ('Spain', 'Italy', 'Finland', 'Germany', 'Russia') 
    </code>
    </pre>
          <br />
          <br />
          <p>
            Thus,<b>we convert the tuple to a list, manipulate items of the list
              using list methods, then convert list back to a tuple.</b>
          </p>
          <br />
          <br />
          <p>
            However, we can directly concatenate two tuples instead of
            converting them to list and back.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        countries = ("Pakistan", "Afghanistan", "Bangladesh", "ShriLanka")
        countries2 = ("Vietnam", "India", "China")
        southEastAsia = countries + countries2
        print(southEastAsia)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ('Pakistan', 'Afghanistan', 'Bangladesh', 'ShriLanka', 'Vietnam', 'India', 'China')
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div27" style="display: none">
          <h2>Unpack Tuples</h2>
          <br />
          <p>
            Unpacking is the process of assigning the tuple items as values to
            variables.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = ("Marcus", 20, "MIT")
        (name, age, university) = info
        print("Name:", name)
        print("Age:",age)
        print("Studies at:",university)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Name: Marcus
        Age: 20
        Studies at: MIT
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here, the number of list items is equal to the number of
            variables.
          </p>
          <br />
          <br />
          <b>But what if we have more number of items then the variables?</b><br />
          <p>
            You can add an * to one of the variables and depending upon the
            position of variable and number of items, python matches variables
            to values and assigns it to the variables.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        fauna = ("cat", "dog", "horse", "pig", "parrot", "salmon")
        (*animals, bird, fish) = fauna
        print("Animals:", animals)
        print("Bird:", bird)
        print("Fish:", fish)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Animals: ['cat', 'dog', 'horse', 'pig']
        Bird: parrot
        Fish: salmon
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        fauna = ("cat", "dog", "horse", "pig", "parrot", "salmon")
        (*animals, bird, fish) = fauna
        print("Animals:", animals)
        print("Bird:", bird)
        print("Fish:", fish)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Animals: ['cat', 'dog', 'horse', 'pig']
        Bird: parrot
        Fish: salmon
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 3:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        fauna = ("parrot", "salmon", "cat", "dog", "horse", "pig")
        (bird, fish, *animals) = fauna
        print("Animals:", animals)
        print("Bird:", bird)
        print("Fish:", fish)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Animals: ['cat', 'dog', 'horse', 'pig']
        Bird: parrot
        Fish: salmon
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div28" style="display: none">
          <h2>Python Sets</h2>
          <br />
          <p>
            Sets are unordered collection of data items. They store multiple
            items in a single variable. Sets items are separated by commas and
            enclosed within curly brackets {}. Sets are unchangeable, meaning
            you cannot change items of the set once created. Sets do not
            contain duplicate items.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {"Carla", 19, False, 5.9, 19}
        print(info)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {False, 19, 5.9, 'Carla'}
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here we see that the items of set occur in random order and hence
            they cannot be accessed using index numbers. Also sets do not
            allow duplicate values.
          </p>
          <br />
          <br />
          <h3>Accessing set items:</h3>
          <br />
          <br />
          <h3>Using a For loop</h3>
          <br />
          <p>You can access items of set using a for loop.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {"Carla", 19, False, 5.9}
        for item in info:
            print(item)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
        Carla
        19
        5.9
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div29" style="display: none">
          <h2>Add/Remove Set Items</h2>
          <br />
          <h3>Add items to set:</h3>
          <br />
          <p>
            If you want to add a single item to the set use the add() method.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities.add("Helsinki")
        print(cities) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Tokyo', 'Helsinki', 'Madrid', 'Berlin', 'Delhi'}
    </code>
    </pre>
          <br />
          <br />
          <p>
            If you want to add more than one item, simply create another set
            or any other iterable object(list, tuple, dictionary), and use the
            update() method to add it into the existing set.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Helsinki", "Warsaw", "Seoul"}
        cities.update(cities2)
        print(cities)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Seoul', 'Berlin', 'Delhi', 'Tokyo', 'Warsaw', 'Helsinki', 'Madrid'}
    </code>
    </pre>
          <br />
          <br />
          <h3>Remove items from set:</h3>
          <br />
          <p>
            We can use remove() and discard() methods to remove items form
            list.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities.remove("Tokyo")
        print(cities)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Delhi', 'Berlin', 'Madrid'}
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities.discard("Delhi")
        print(cities)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Berlin', 'Tokyo', 'Madrid'} 
    </code>
    </pre>
          <br />
          <br />
          <p>
            The main difference between remove and discard is that, if we try
            to delete an item which is not present in set, then remove()
            raises an error, whereas discard() does not raise any error.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities.remove("Seoul")
        print(cities)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        KeyError: 'Seoul'
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities.discard("Seoul")
        print(cities)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Madrid', 'Delhi', 'Tokyo', 'Berlin'}
    </code>
    </pre>
          <br />
          <br />
          <h3>
            There are various other methods to remove items from the set:
            pop(), del(), clear().
          </h3>
          <br />
          <br />
          <h3>pop():</h3>
          <br />
          <p>
            This method removes the last item of the set but the catch is that
            we don’t know which item gets popped as sets are unordered.
            However, you can access the popped item if you assign the pop()
            method to a variable.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        item = cities.pop()
        print(cities)
        print(item)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Tokyo', 'Delhi', 'Berlin'}
        Madrid
    </code>
    </pre>
          <br />
          <br />
          <h3>del:</h3>
          <br />
          <p>
            del is not a method, rather it is a keyword which deletes the set
            entirely.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        del cities
        print(cities)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        NameError: name 'cities' is not defined 
    </code>
    </pre>
          <br />
          <br />
          <p>
            We get an error because our entire set has been deleted and there
            is no variable called cities which contains a set.
          </p>
          <br />
          <b>What if we don’t want to delete the entire set, we just want to
            delete all items within that set?</b><br />
          <br />
          <h3>clear():</h3>
          <br />
          <p>
            This method clears all items in the set and prints an empty set.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities.clear()
        print(cities)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        set()
    </code>
    </pre>
          <br />
          <br />
          <h3>Check if items exists</h3>
          <br />
          <p>You can also check if an item exists in the set or not.</p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {"Carla", 19, False, 5.9}
        if "Carla" in info:
            print("Carla is present.")
        else:
            print("Carla is absent.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Carla is present.
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {"Carla", 19, False, 5.9}
        if "Carmen" in info:
            print("Carmen is present.")
        else:
            print("Carmen is absent.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Carmen is absent.
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div30" style="display: none">
          <h2>Join Sets</h2>
          <br />
          <p>
            Sets in python more or less work in the same way as sets in
            mathematics. We can perform operations like union and intersection
            on the sets just like in mathematics.
          </p>
          <br />
          <br />
          <h3>1. union() and update():</h3>
          <br />
          <p>
            The union() and update() methods prints all items that are present
            in the two sets. The union() method returns a new set whereas
            update() method adds item into the existing set from another set.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
cities2 = {"Tokyo", "Seoul", "Kabul", "Madrid"}
cities3 = cities.union(cities2)
print(cities3)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Tokyo', 'Madrid', 'Kabul', 'Seoul', 'Berlin', 'Delhi'}
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Tokyo", "Seoul", "Kabul", "Madrid"}
        cities.update(cities2)
        print(cities)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Berlin', 'Madrid', 'Tokyo', 'Delhi', 'Kabul', 'Seoul'} 
    </code>
    </pre>
          <br />
          <br />
          <h3>2. intersection and intersection_update():</h3>
          <br />
          <p>
            The intersection() and intersection_update() methods prints only
            items that are similar to both the sets. The intersection() method
            returns a new set whereas intersection_update() method updates
            into the existing set from another set.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Tokyo", "Seoul", "Kabul", "Madrid"}
        cities3 = cities.intersection(cities2)
        print(cities3)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Madrid', 'Tokyo'}
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Tokyo", "Seoul", "Kabul", "Madrid"}
        cities.intersection(cities2)
        print(cities)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Tokyo', 'Madrid'}
    </code>
    </pre>
          <br />
          <br />
          <h3>3. symmetric_difference and symmetric_difference_update():</h3>
          <br />
          <p>
            The symmetric_difference() and symmetric_difference_update()
            methods prints only items that are not similar to both the sets.
            The symmetric_difference() method returns a new set whereas
            symmetric_difference_update() method updates into the existing set
            from another set.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Tokyo", "Seoul", "Kabul", "Madrid"}
        cities3 = cities.symmetric_difference(cities2)
        print(cities3)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Seoul', 'Kabul', 'Berlin', 'Delhi'}
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Tokyo", "Seoul", "Kabul", "Madrid"}
        cities.symmetric_difference_update(cities2)
        print(cities) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Kabul', 'Delhi', 'Berlin', 'Seoul'}
    </code>
    </pre>
          <br />
          <br />
          <h3>4. difference() and difference_update():</h3>
          <br />
          <p>
            The difference() and difference_update() methods prints only items
            that are only present in the original set and not in both the
            sets. The difference() method returns a new set whereas
            difference_update() method updates into the existing set from
            another set.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Seoul", "Kabul", "Delhi"}
        cities3 = cities.difference(cities2)
        print(cities3)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Tokyo', 'Madrid', 'Berlin'}
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Seoul", "Kabul", "Delhi"}
        print(cities.difference(cities2))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'Tokyo', 'Berlin', 'Madrid'}
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div31" style="display: none">
          <h2>Set Methods</h2>
          <br />
          <p>
            Apart from the methods we discussed earlier in the chapter there
            are some more methods that we can use to manipulate sets.
          </p>
          <br />
          <br />
          <b>What if you want to check if items of a particular set are
            present in another set?</b><br />
          <p>There are a few methods to check this.</p>
          <br />
          <h3>isdisjoint():</h3>
          <br />
          <p>
            The isdisjoint() method checks if items of given set are present
            in another set. This method returns False if items are present,
            else it returns True.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Tokyo", "Seoul", "Kabul", "Madrid"}
        print(cities.isdisjoint(cities2))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
         False
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Seoul", "Kabul"}
        print(cities.isdisjoint(cities2))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h3>issuperset():</h3>
          <br />
          <p>
            The issuperset() method checks if all the items of a particular
            set are present in the original set. It returns True if all the
            items are present, else it returns False.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Seoul", "Kabul"}
        print(cities.issuperset(cities2))
        cities3 = {"Seoul", "Madrid","Kabul"}
        print(cities.issuperset(cities3))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
         False
         False
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Delhi", "Madrid"}
        print(cities.issuperset(cities2))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        True
    </code>
    </pre>
          <br />
          <br />
          <h3>issubset():</h3>
          <br />
          <p>
            The issubset() method checks if all the items of the original set
            are present in the particular set. It returns True if all the
            items are present, else it returns False.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Delhi", "Madrid"}
        print(cities2.issubset(cities))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
         True
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        cities = {"Tokyo", "Madrid", "Berlin", "Delhi"}
        cities2 = {"Seoul", "Kabul"}
        print(cities2.issubset(cities))
        cities3 = {"Seoul", "Madrid", "Kabul"}
        print(cities3.issubset(cities))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        False
        False
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div32" style="display: none">
          <h2>Python Dictionaries</h2>
          <br />
          <p>
            Dictionaries are ordered collection of data items. They store
            multiple items in a single variable. Dictionaries items are
            key-value pairs that are separated by commas and enclosed within
            curly brackets {}.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True}
        print(info)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'name': 'Karan', 'age': 19, 'eligible': True}
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div33" style="display: none">
          <h2>Access Items</h2>
          <br />
          <h3>Accessing Dictionary items:</h3>
          <br />
          <br />
          <h3>1.Accessing single values:</h3>
          <br />
          <p>
            Values in a dictionary can be accessed using keys. We can access
            dictionary values by mentioning keys either in square brackets or
            by using get method.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True}
        print(info['name'])
        print(info.get('eligible'))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Karan
        True
    </code>
    </pre>
          <br />
          <br />
          <h3>2. Accessing multiple values:</h3>
          <br />
          <p>
            We can print all the values in the dictionary using values()
            method.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True}
        print(info.values())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        dict_values(['Karan', 19, True])
    </code>
    </pre>
          <br />
          <br />
          <h3>3.Accessing keys:</h3>
          <br />
          <p>
            We can print all the keys in the dictionary using keys() method.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True}
        print(info.keys())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        dict_keys(['name', 'age', 'eligible'])
    </code>
    </pre>
          <br />
          <br />
          <h3>Accessing key-value pairs:</h3>
          <br />
          <p>
            We can print all the key-value pairs in the dictionary using
            items() method.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True}
        print(info.items())
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        dict_items([('name', 'Karan'), ('age', 19), ('eligible', True)])
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div34" style="display: none">
          <h2>Add/Remove Items</h2>
          <br />
          <h3>Adding items to dictionary:</h3>
          <br />
          <p>There are two ways to add items to a dictionary.</p>
          <br />
          <h3>1. Create a new key and assign a value to it:</h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True}
        print(info)
        info['DOB'] = 2001
        print(info) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'name': 'karan', 'age': 19, 'eligible': True}
        {'name': 'karan', 'age': 19, 'eligible': True, 'DOB': 2001}
    </code>
    </pre>
          <br />
          <br />
          <h3>2.Use the update() method:</h3>
          <br />
          <p>
            The update() method updates the value of the key provided to it if
            the item already exists in the dictionary, else it creates a new
            key-value pair.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True}
        print(info)
        info.update({'age':20})
        info.update({'DOB':2001})
        print(info)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'name': 'karan', 'age': 19, 'eligible': True}
        {'name': 'karan', 'age': 20, 'eligible': True, 'DOB': 2001}
    </code>
    </pre>
          <br />
          <br />
          <h3>Removing items from dictionary:</h3>
          <br />
          <p>
            There are a few methods that we can use to remove items from
            dictionary.
          </p>
          <br />
          <br />
          <h3>
            clear(): The clear() method removes all the items from the list.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True}
        info.clear()
        print(info)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
       {}
    </code>
    </pre>
          <br />
          <br />
          <h3>
            pop(): The pop() method removes the key-value pair whose key is
            passed as a parameter.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True}
        info.pop('eligible')
        print(info)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'name': 'Karan', 'age': 19}
    </code>
    </pre>
          <br />
          <br />
          <h3>
            popitem(): The popitem() method removes the last key-value pair
            from the dictionary.
          </h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True, 'DOB':2003}
        info.popitem()
        print(info)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'name': 'Karan', 'age': 19, 'eligible': True}
    </code>
    </pre>
          <br />
          <br />
          <p>
            apart from these three methods, we can also use the del keyword to
            remove a dictionary item.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True, 'DOB':2003}
        del info['age']
        print(info)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'name': 'Karan', 'eligible': True, 'DOB': 2003}
    </code>
    </pre>
          <br />
          <br />
          <p>
            If key is not provided, then the del keyword will delete the
            dictionary entirely.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True, 'DOB':2003}
        del info
        print(info)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        NameError: name 'info' is not defined
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div35" style="display: none">
          <h2>Copy Dictionaries</h2>
          <br />
          <p>
            We can use the copy() method to copy the contents of one
            dictionary into another dictionary.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True, 'DOB':2003}
        newDictionary = info.copy()
        print(newDictionary)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'name': 'Karan', 'age': 19, 'eligible': True, 'DOB': 2003}
    </code>
    </pre>
          <br />
          <br />
          <p>
            Or we can use the <b>dict() function</b> to make a new dictionary
            with the items of original dictionary.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        info = {'name':'Karan', 'age':19, 'eligible':True, 'DOB':2003}
        newDictionary = dict(info)
        print(newDictionary)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        {'name': 'Karan', 'age': 19, 'eligible': True, 'DOB': 2003}
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div36" style="display: none">
          <h2>if Statement</h2>
          <br />
          <p>
            Sometimes the programmer needs to check the evaluation of certain
            expression(s), whether the expression(s) evaluate to True or
            False. If the expression evaluates to False, then the program
            execution follows a different path then it would have if the
            expression had evaluated to True.
            <br />
            Based on this,
            <b>the conditional statements are further classified into
              following types; if, if……else, elif, nested if.</b>
          </p>
          <br />
          <br />
          <h3>if Statement:</h3>
          <br />
          <p>A simple if statement works on following principle,</p>
          <br />
          <li>
            execute the block of code inside if statement if the expression
            evaluates True.
          </li>
          <li>
            ignore the block of code inside if statement if the expression
            evaluates False and return to the code outside if statement.
          </li>
          <br />
          <img
            src="https://cwh-full-next-space.fra1.digitaloceanspaces.com/tutorial/python-if-statement/if_statement.png"
            alt="" /><br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        applePrice = 180
        budget = 200
        if (applePrice &lt;= budget):
            print("Alexa, add 1kg Apples to the cart.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Alexa, add 1kg Apples to the cart.
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div37" style="display: none">
          <h2>if-else Statement</h2>
          <br />
          <b>An if……else statement works on the following principle,</b><br />
          <li>
            execute the block of code inside if statement if the expression
            evaluates True. After execution return to the code out of the
            if……else block.
          </li>
          <li>
            execute the block of code inside else statement if the expression
            evaluates False. After execution return to the code out of the
            if……else block.
          </li>
          <br />
          <img
            src="https://cwh-full-next-space.fra1.digitaloceanspaces.com/tutorial/python-if-else-statement/if-else.png"
            alt="" /><br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        applePrice = 210
        budget = 200
        if (applePrice &lt;= budget):
            print("Alexa, add 1kg Apples to the cart.")
        else:
            print("Alexa, do not add Apples to the cart.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Alexa, do not add Apples to the cart.
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div38" style="display: none">
          <h2>elif statement</h2>
          <br />
          <p>
            Sometimes, the programmer may want to evaluate more than one
            condition, this can be done using an elif statement.
          </p>
          <br />
          <br />
          <b>An elif statement works on the following principle,</b><br />
          <li>
            execute the block of code inside if statement if the initial
            expression evaluates to True. After execution return to the code
            out of the if block.
          </li>
          <li>
            execute the block of code inside the first elif statement if the
            expression inside it evaluates True. After execution return to the
            code out of the if block.
          </li>
          <li>
            execute the block of code inside the second elif statement if the
            expression inside it evaluates True. After execution return to the
            code out of the if block. <br />
            . <br />
            . <br />
            .
          </li>
          <li>
            execute the block of code inside the nth elif statement if the
            expression inside it evaluates True. After execution return to the
            code out of the if block.
          </li>
          <li>
            execute the block of code inside else statement if none of the
            expression evaluates to True. After execution return to the code
            out of the if block.
          </li>
          <br />
          <img src="https://cwh-full-next-space.fra1.digitaloceanspaces.com/tutorial/python-elif-statement/elif.png"
            alt="" /><br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        num = 0
if (num &lt; 0):
    print("Number is negative.")
elif (num == 0):
    print("Number is Zero.")
else:
    print("Number is positive.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Number is Zero.
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div39" style="display: none">
          <h2>Nested if Statement</h2>
          <br />
          <p>
            We can use if, if….else, elif statements inside other if
            statements.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        num = 18
        if (num &lt; 0):
            print("Number is negative.")
        elif (num &gt; 0):
            if (num &lt;= 10):
                print("Number is between 1-10")
            elif (num &gt; 10 and num &lt;= 20):
                print("Number is between 11-20")
            else:
                print("Number is greater than 20")
        else:
            print("Number is zero")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Number is between 11-20.
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div40" style="display: none">
          <h2>Python for Loop</h2>
          <br />
          <p>
            Sometimes a programmer wants to execute a group of statements a
            certain number of times. This can be done using loops. Based on
            this loops are further classified into following types;
            <b>for loop, while loop, nested loops.</b>
          </p>
          <br />
          <br />
          <h3>for Loop</h3>
          <br />
          <p>
            for loops can iterate over a sequence of iterable objects in
            python. Iterating over a sequence is nothing but iterating over
            strings, lists, tuples, sets and dictionaries.
          </p>
          <br />
          <p><b>Example:</b> iterating over a string:</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        name = 'Abhishek'
        for i in name:
            print(i, end=", ")    
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        A, b, h, i, s, h, e, k,   
    </code>
    </pre>
          <br />
          <br />
          <p><b>Example:</b> iterating over a tuple:</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        colors = ("Red", "Green", "Blue", "Yellow")
        for x in colors:
            print(x) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Red
        Green
        Blue
        Yellow
    </code>
    </pre>
          <br />
          <br />
          <p>
            similarly,<b>we can use loops for lists, sets and dictionaries.</b>
          </p>
          <br />
          <img src="https://cwh-full-next-space.fra1.digitaloceanspaces.com/tutorial/python-for-loops/for.png"
            alt="" /><br />
          <b>What if we do not want to iterate over a sequence? What if we
            want to use for loop for a specific number of times?</b><br />
          <p>Here, we can use the range() function.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        for k in range(5):
        print(k)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        0
        1
        2
        3
        4
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here, we can see that the loop starts from 0 by default and
            increments at each iteration.
          </p>
          <br />
          <b>But we can also loop over a specific range.</b><br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        for k in range(4,9):
        print(k)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        4
        5
        6
        7
        8
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div41" style="display: none">
          <h2>Python while Loop</h2>
          <br />
          <p>
            As the name suggests, while loops execute statements while the
            condition is True. As soon as the condition becomes False, the
            interpreter comes out of the while loop.
          </p>
          <br />
          <img src="https://cwh-full-next-space.fra1.digitaloceanspaces.com/tutorial/python-while-loop/while.png"
            alt="" />
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        count = 5
        while (count > 0):
            print(count)
            count = count - 1
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        5
        4
        3
        2
        1
    </code>
    </pre>
          <br />
          <br />
          <p>
            Here, the count variable is set to 5 which decrements after each
            iteration. Depending upon the while loop condition, we need to
            either increment or decrement the counter variable (the variable
            count, in our case) or the loop will continue forever.
          </p>
          <br />
          <p>
            We can even use the else statement with the while loop.
            Essentially what the else statement does is that as soon as the
            while loop condition becomes False, the interpreter comes out of
            the while loop and the else statement is executed.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        x = 5
        while (x > 0):
            print(x)
            x = x - 1
        else:
            print('counter is 0')
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        5
        4
        3
        2
        1
        counter is 0
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div42" style="display: none">
          <h2>Nested Loops</h2>
          <br />
          <p>
            We can use loops inside other loops, such types of loops are
            called as nested loops.
          </p>
          <br />
          <p><b>Example:</b>nesting for loop in while loop</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        while (i&lt;=3):
        for k in range(1, 4):
            print(i, "*", k, "=", (i*k))
        i = i + 1
        print()
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        1 * 1 = 1
        1 * 2 = 2
        1 * 3 = 3
        
        2 * 1 = 2
        2 * 2 = 4
        2 * 3 = 6
        
        3 * 1 = 3
        3 * 2 = 6
        3 * 3 = 9
        
    </code>
    </pre>
          <br />
          <br />
          <p><b>Example:</b>nesting while loop in for loop</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        for i in range(1, 4):
        k = 1
        while (k&lt;=3):
            print(i, "*", k, "=", (i*k))
            k = k + 1
        print()
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        1 * 1 = 1
        1 * 2 = 2
        1 * 3 = 3
        
        2 * 1 = 2
        2 * 2 = 4
        2 * 3 = 6
        
        3 * 1 = 3
        3 * 2 = 6
        3 * 3 = 9
        
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div43" style="display: none">
          <h2>Control Statements</h2>
          <br />
          <p>
            There are three control statements that can be used with for and
            while loops to alter their behaviour.
            <br />
            They are <b>pass, continue and break.</b>
          </p>
          <br />
          <br />
          <h3>1. pass:</h3>
          <br />
          <p>
            Whenever loops, functions, if statements, classes, etc are
            created, it is needed that we should write a block of code in it.
            An empty code inside loop, if statement or function will give an
            error.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        i = 1
        while (i&lt;5): 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        IndentationError: expected an indented block
    </code>
    </pre>
          <br />
          <br />
          <p>
            To avoid such an error and to continue the code execution, pass
            statement is used. pass statement acts as a placeholder for future
            code.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        i = 1
        while (i&lt;5):
            pass
        
        for j in range(5):
            pass
        
        if (i == 2):
            pass
    </code>   
    </pre>
          <br />
          <br />
          <p>The above code does not give an error.</p>
          <br />
          <br />
          <h3>2. continue:</h3>
          <br />
          <p>
            This keyword is used in loops to end the current iteration and
            continue the next iteration of the loop. Sometimes within a loop,
            we might need to skip a specific iteration. This can be done using
            the continue keyword.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        for i in range(1,10):
        if(i%2 == 0):
            continue   
        print(i)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        1
        3
        5
        7
        9
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        i = 1
        while (i &lt;= 10):
            i = i + 1
            if (i%2 != 0):
                continue
            print(i)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        2
        4
        6
        8
        10
    </code>
    </pre>
          <br />
          <br />
          <h3>3. break</h3>
          <br />
          <p>
            The break keyword is used to bring the interpreter out of the loop
            and into the main body of the program. Whenever the break keyword
            is used, the loop is terminated and the interpreter starts
            executing the next series of statements within the main program.
          </p>
          <br />
          <h4>Example 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        i = 1
        while (i &lt;= 10):
            i = i + 1
            if (i == 5):
                break
            print(i)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        2
        3
        4
    </code>
    </pre>
          <br />
          <br />
          <h4>Example 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        for i in range(1, 10):
        print(i)
        if (i == 5):
            break
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        1
        2
        3
        4
        5
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div44" style="display: none">
          <h2>Python Functions</h2>
          <br />
          <p>
            A function is a block of code that performs a specific task
            whenever it is called. In bigger programs, where we have large
            amounts of code, it is advisable to create or use existing
            functions that make the program flow organized and neat.
          </p>
          <br /><br />
          <b>There are two types of functions:</b><br />
          <li>built-in functions</li>
          <li>user-defined functions</li>
          <br />
          <br />
          <h3>1. built-in functions:</h3>
          <br />
          <p>
            These functions are defined and pre-coded in python. Some examples
            of built-in functions are as follows:
            <br />
            min(), max(), len(), sum(), type(), range(), dict(), list(),
            tuple(), set(), print(), etc.
          </p>
          <br /><br />
          <h3>2. user-defined functions:</h3>
          <br />
          <p>
            We can create functions to perform specific tasks as per our
            needs. Such functions are called user-defined functions.
          </p>
          <br />
          <h4>Syntax:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        def function_name(parameters):
        Code and Statements  
    </code>   
    </pre>
          <br />
          <br />
          <li>
            Create a function using the def keyword, followed by a function
            name, followed by a paranthesis (()) and a colon(:).
          </li>
          <li>
            Any parameters and arguments should be placed within the
            parentheses.
          </li>
          <li>
            Rules to naming function are similar to that of naming variables.
          </li>
          <li>
            Any statements and other code within the function should be
            indented.
          </li>
          <br />
          <br />
          <h3>Call a function:</h3>
          <br />
          <p>
            We call a function by giving the function name, followed by
            parameters (if any) in the parenthesis.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        def name(fname, lname):
        print("Hello,", fname, lname)
    
    name("Sam", "Wilson")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello, Sam Wilson
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div45" style="display: none">
          <h2>Function Arguments</h2>
          <br />
          <b>There are four types of arguments that we can provide in a
            function:</b><br />
          <li>Default Arguments</li>
          <li>Keyword Arguments</li>
          <li>Required Arguments</li>
          <li>Variable-length Arguments</li>
          <br />
          <br />
          <h3>Default arguments:</h3>
          <br />
          <p>
            We can provide a default value while creating a function. This way
            the function assumes a default value even if a value is not
            provided in the function call for that argument.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
      def name(fname, mname = "Jhon", lname = "Whatson"):
        print("Hello,", fname, mname, lname)
    
      name("Amy")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello, Amy Jhon Whatson
    </code>
    </pre>
          <br />
          <br />
          <h3>Keywords arguments:</h3>
          <br />
          <p>
            We can provide arguments with key = value, this way the
            interpreter recognizes the arguments by the parameter name. Hence,
            the the order in which the arguments are passed does not matter.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
      def name(fname, mname, lname):
        print("Hello,", fname, mname, lname)
    
      name(mname = "Peter", lname = "Wesker", fname = "Jade")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello, Jade Peter Wesker
    </code>
    </pre>
          <br />
          <br />
          <h3>Required arguments</h3>
          <br />
          <p>
            In case we don’t pass the arguments with a key = value syntax,
            then it is necessary to pass the arguments in the correct
            positional order and the number of arguments passed should match
            with actual function definition.
          </p>
          <br />
          <p>
            <b>Example 1:</b> when number of arguments passed does not match
            to the actual function definition.
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
      def name(fname, mname, lname):
        print("Hello,", fname, mname, lname)
    
      name("Peter", "Quill")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        name("Peter", "Quill")
        TypeError: name() missing 1 required positional argument: 'lname'
    </code>
    </pre>
          <br />
          <br />
          <p>
            <b>Example 1:</b> when number of arguments passed matches to the
            actual function definition.
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
      def name(fname, mname, lname):
        print("Hello,", fname, mname, lname)
    
      name("Peter", "Ego", "Quill")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello, Peter Ego Quill
    </code>
    </pre>
          <br />
          <br />
          <h3>Variable-length arguments:</h3>
          <br />
          <p>
            Sometimes we may need to pass more arguments than those defined in
            the actual function. This can be done using variable-length
            arguments.
            <br />
            <b>There are two ways to achieve this:</b>
          </p>
          <br />
          <br />
          <li><b>Arbitrary Arguments:</b></li>
          <br />
          <p>
            While creating a function, pass a * before the parameter name
            while defining the function. The function accesses the arguments
            by processing them in the form of tuple.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        def name(*name):
        print("Hello,", name[0], name[1], name[2])
    
    name("James", "Buchanan", "Barnes")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello, James Buchanan Barnes
    </code>
    </pre>
          <br />
          <br />
          <li><b>Keyword Arbitrary Arguments:</b></li>
          <br />
          <p>
            While creating a function, pass a * before the parameter name
            while defining the function. The function accesses the arguments
            by processing them in the form of dictionary.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        def name(**name):
        print("Hello,", name["fname"], name["mname"], name["lname"])
    
    name(mname = "Buchanan", lname = "Barnes", fname = "James")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello, James Buchanan Barnes
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div46" style="display: none">
          <h2>return Statement</h2>
          <br />
          <p>
            The return statement is used to return the value of the expression
            back to the main function.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        def name(fname, mname, lname):
        return "Hello, " + fname + " " + mname + " " + lname
    
    print(name("James", "Buchanan", "Barnes"))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello, James Buchanan Barnes
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div47" style="display: none">
          <h2>Python Recursion</h2>
          <br />
          <p>
            We can let the function call itself, such a process is known as
            calling a function recursively in python.
          </p>
          <br />
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        def factorial(num): 
        if (num == 1 or num == 0):
            return 1
        else:
            return (num * factorial(num - 1)) 
      
    # Driver Code 
    num = 7; 
    print("number: ",num)
    print("Factorial: ",factorial(num)) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        number:  7
        Factorial:  5040
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div48" style="display: none">
          <h2>Python Modules</h2>
          <br />
          <p>
            Python modules are python files that contain python code that we
            can use within our python files ensuring simplicity and code
            reusability.
          </p>
          <br />
          <br />
          <p>
            <b>Here are some popular python built-in modules:</b>
            <br />
            csv, datetime, json, math, random, sqlite3, statistics, tkinter,
            turtle, etc.
          </p>
          <br />
          <br />
          <p><b>Example:</b> importing math module:</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import math

        print("Sin(0) =", math.sin(0))
        print("Sin(30) =", math.sin(math.pi/6))
        print("Sin(45) =", math.sin(math.pi/4))
        print("Sin(60) =", math.sin(math.pi/3))
        print("Sin(90) =", math.sin(math.pi/2)) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Sin(0) = 0.0
        Sin(30) = 0.49999999999999994
        Sin(45) = 0.7071067811865476
        Sin(60) = 0.8660254037844386
        Sin(90) = 1.0
    </code>
    </pre>
          <br />
          <br />
          <p>
            Apart from this we can create our own modules and use them within
            other python files.
          </p>
          <br />
          <br />
          <h3>A. Creating and using module:</h3>
          <br />
          <p>Write code and save file with extension .py .</p>
          <br />
          <p>
            <b>Example:</b> creating file module.py and writing some code:
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        def add(a, b):
        return (a+b)
    
    def sub(a, b):
        return (a-b)
    
    def mul(a, b):
        return (a*b)
    
    def div(a, b):
        return (a/b)
    </code>   
    </pre>
          <br />
          <br />
          <p>
            Now we can use this code in a different python file by simply
            using the import statement.
          </p>
          <br />
          <p><b>Example:</b> creating file calc.py and importing module.py</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import module 
    </code>   
    </pre>
          <br />
          <br />
          <p>
            Now we can write code to call the functions from module.py in
            calc.py
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import module 

        num1 = int(input("Enter first number:"))
        num2 = int(input("Enter second number:"))
        
        print("Addition", module.add(num1, num2))
        print("Subtraction", module.sub(num1, num2))
        print("Multiplication", module.mul(num1, num2))
        print("Division", module.div(num1, num2)) 
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Enter first number:6
        Enter second number:2
        Addition 8
        Subtraction 4
        Multiplication 12
        Division 3.0
    </code>
    </pre>
          <br />
          <br />
          <h3>B. Using an alias:</h3>
          <br />
          <p>
            We can also use alias while importing module. This way we do not
            need to write the whole name of the module while calling it.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import math as m

        print("Square Root of 36 :", m.sqrt(36))
        print("3 to the power of 4 :", m.pow(3,4))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Square Root of 36 : 6.0
        3 to the power of 4 : 81.0
    </code>
    </pre>
          <br />
          <br />
          <h3>C. impoert from module:</h3>
          <br />
          <p>
            You can also import specific parts that you need from a module
            instead of importing the entire module.
          </p>
          <br />
          <p><b>Example:</b>creating file module.py and writing some code:</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        def add(a, b):
        return (a+b)
    
    def sub(a, b):
        return (a-b)
    
    def mul(a, b):
        return (a*b)
    
    def div(a, b):
        return (a/b)   
    </code>   
    </pre>
          <br />
          <br />
          <p>
            <b>Example:</b> now we will only import add() and sub() function
            into our calc.py file.
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        from module import add, sub 

        num1 = int(input("Enter first number:"))
        num2 = int(input("Enter second number:"))
        
        print("Addition", add(num1, num2))
        print("Subtraction", sub(num1, num2))
        print("Multiplication", mul(num1, num2))
        print("Division", div(num1, num2))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Enter first number:12
        Enter second number:4
        Addition 16
        Subtraction 8
        Traceback (most recent call last):
        File "d:\Python\Codes\calc.py", line 9, in &lt;module&gt;
            print("Multiplication", mul(num1, num2))
        NameError: name 'mul' is not defined
    </code>
    </pre>
          <br />
          <br />
          <p>
            As we can see that, we have only imported add() and sub()
            functions from module.py file. Hence we get output for these
            functions, but we get error if we use any other functions.
          </p>
          <br />
          <br />
          <p>
            <b>But what if want to import everything from a module but we do
              not need to prefix module name again and again?</b>
            <br />
            Use an asterisk(*) while importing.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        from module import *

        num1 = int(input("Enter first number:"))
        num2 = int(input("Enter second number:"))
        
        print("Addition", add(num1, num2))
        print("Subtraction", sub(num1, num2))
        print("Multiplication", mul(num1, num2))
        print("Division", div(num1, num2))
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Enter first number:12
        Enter second number:4
        Addition 16
        Subtraction 8
        Multiplication 48
        Division 3.0
    </code>
    </pre>
          <br />
          <br />
          <p>
            As we can see, by using an asterisk(*), we can directly call the
            functions from the imported module without prefixing it with
            module name.
          </p>
          <br />
          <br />
          <h3>D. dir() Function:</h3>
          <br />
          <p>
            The dir() function lists all the function names (or variable
            names) in a module.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        from operator import mod
        import math
        
        lst1 = dir(math)
        print(lst1)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['__doc__', '__loader__', '__name__', '__package__', '__spec__', 'acos', 'acosh', 'asin', 'asinh', 'atan', 'atan2', 'atanh', 'ceil', 'comb', 'copysign', 'cos', 'cosh', 'degrees', 'dist', 'e', 'erf', 'erfc', 'exp', 'expm1', 'fabs', 'factorial', 'floor', 'fmod', 'frexp', 'fsum', 'gamma', 'gcd', 'hypot', 'inf', 'isclose', 'isfinite', 'isinf', 'isnan', 'isqrt', 'lcm', 'ldexp', 'lgamma', 'log', 'log10', 'log1p', 'log2', 'modf', 'nan', 'nextafter', 'perm', 'pi', 'pow', 'prod', 'radians', 'remainder', 'sin', 'sinh', 'sqrt', 'tan', 'tanh', 'tau', 'trunc', 'ulp']  
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div49" style="display: none">
          <h2>Python Packages</h2>
          <br />
          <p>
            Python packages are essentially folders that contain many python
            modules. As such, packages help us to import modules from
            different folders.
          </p>
          <br />
          <br />
          <p>
            <b>Here are some packages provided by python,</b>
            <br />
            NumPy, SciPy, Pandas, Seaborn, sklearn, Matplotlib, etc.
          </p>
          <br />
          <br />
          <p>
            We will learn more about these python packages in later chapters.
          </p>
          <br />
          <br />
        </div>
        <div class="notes" id="div50" style="display: none">
          <h2>Python OOPS</h2>
          <br />
          <p>
            A class is a blueprint or a template for creating objects while an
            object is an instance or a copy of the class with actual values.
          </p>
          <br />
          <br />
          <h3>Creating a class:</h3>
          <br />
          <p>Create a class using the class keyword.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        class Details:
        name = "Simran"
        age = 20
    </code>   
    </pre>
          <br />
          <br />
          <h3>Creating an Object:</h3>
          <br />
          <p>Now create object of the class.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        obj1 = Details()
        print(obj1.name)
        print(obj1.age)
    </code>   
    </pre>
          <br />
          <br />
          <p>Now we can print values:</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        class Details:
        name = "Simran"
        age = 20

        obj1 = Details()
        print(obj1.name)
        print(obj1.age)
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Simran
        20
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div51" style="display: none">
          <h2>Self Method</h2>
          <br />
          <p>
            The self parameter is a reference to the current instance of the
            class, and is used to access variables that belongs to the class.
            <br />
            It must be provided as the extra parameter inside the method
            definition.
          </p>
          <br />
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        class Details:
        name = "Simran"
        age = 20
    
        def desc(self):
            print("My name is", self.name, "and I'm", self.age, "years old.")
    
    obj1 = Details()
    obj1.desc()
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        My name is Simran and I'm 20 years old.
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div52" style="display: none">
          <h2>_init_ method</h2>
          <br />
          <p>
            The __init__ method is used to initialize the object’s state and
            contains statements that are executed at the time of object
            creation.
          </p>
          <br />
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        class Details:
        def __init__(self, animal, group):
            self.animal = animal
            self.group = group
    
    obj1 = Details("Crab", "Crustaceans")
    print(obj1.animal, "belongs to the", obj1.group, "group.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Crab belongs to the Crustaceans group.
    </code>
    </pre>
          <br />
          <br />
          <p>We can also modify and delete objects and their properties:</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        class Details:
        def __init__(self, animal, group):
            self.animal = animal
            self.group = group
    
        obj1 = Details("Crab", "Crustaceans")
        obj1.animal = "Shrimp"  #Modify object property
        print(obj1.animal, "belongs to the", obj1.group, "group.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Shrimp belongs to the Crustaceans group.
    </code>
    </pre>
          <br />
          <br />
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        class Details:
        def __init__(self, animal, group):
            self.animal = animal
            self.group = group
    
    obj1 = Details("Crab", "Crustaceans")
    del obj1    #delete object entirely
    print(obj1.animal, "belongs to the", obj1.group, "group.")
    </code>   
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Traceback (most recent call last):
        File "d:\Python \Codes\class.py", line 12, in &lt;module&gt;
          print(obj1.animal, "belongs to the", obj1.group, "group.")
      NameError: name 'obj1' is not defined
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div53" style="display: none">
          <h2>Python Iterators</h2>
          <br />
          <p>
            Iterators in python are used to iterate over iterable objects or
            container datatypes like lists, tuples, dictionaries, sets, etc.
          </p>
          <br />
          <br />
          <p>
            It consists of __iter__() and __next__() methods.
            <br />
            <b> __iter__() :</b> to initialize an iterator, use the __iter__()
            method.
            <br />
            <b>__next__() :</b> This method returns the next item of the
            sequence.
          </p>
          <br />
          <br />
          <h3>Using inbuilt iterators:</h3>
          <br />
          <pre class="highlight">
    <code class="language-js">
        string = 'Hello World'
        iterObj = iter(string)
        
        while True:
            try:
                char1 = next(iterObj)
                print(char1)
            except StopIteration:
                break    
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        H
        e
        l
        l
        o
        
        W
        o
        r
        l
        d
    </code>
    </pre>
          <br />
          <br />
          <h3>Creating Custom iterators:</h3>
          <br />
          <pre class="highlight">
    <code class="language-js">
        class multipleOf4:
        def __iter__(self):
          self.count = 0
          return self
      
        def __next__(self):
          if self.count &lt;= 24:
            x = self.count
            self.count += 4
            return x
          else:
            raise StopIteration
      
      obj1 = multipleOf4()
      number = iter(obj1)
      
      for x in number:
        print(x)     
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        0
        4
        8
        12
        16
        20
        24
    </code>
    </pre>
          <br />
          <br />
          <p>
            In both the above examples, we can see that there is an
            StopIteration statement inside the except block. This is to
            prevent the iteration from continuing forever.
          </p>
          <br />
          <br />
        </div>
        <div class="notes" id="div54" style="display: none">
          <h2>JSON</h2>
          <br />
          <p>
            JSON stands for JavaScript Object Notation. It is a built-in
            package provided in python that is used to store and exchange
            data.
          </p>
          <br />
          <br />
          <h3>A. Converting JSON string to python:</h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import json

        # JSON String:
        colors =  '["Red", "Yellow", "Green", "Blue"]'
        
        # JSON string to python dictionary:
        lst1 = json.loads(colors)
        print(lst1)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Red', 'Yellow', 'Green', 'Blue']
    </code>
    </pre>
          <br />
          <br />
          <h3>B. Converting python to JSON string:</h3>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import json

        # python dictionary
        lst1 = ['Red', 'Yellow', 'Green', 'Blue']
        
        # Convert Python dict to JSON
        jsonObj = json.dumps(lst1)
        print(jsonObj)
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        ['Red', 'Yellow', 'Green', 'Blue']
    </code>
    </pre>
          <br />
          <br />
          <h3>C. Conversion type:</h3>
          <br />
          <p>
            Whenever python objects are converted to JSON, object type is
            changed to match that of JSON.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import json

        print(json.dumps(22))               #integer
        print(json.dumps(6.022))            #float
        print(json.dumps("Hello World"))    #string
        print(json.dumps(True))             #True
        print(json.dumps(False))            #False
        print(json.dumps(None))             #None
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        22
        6.022
        "Hello World"
        true
        false
        null
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div55" style="display: none">
          <h2>Python try...except</h2>
          <br />
          <p>
            try….. except blocks are used in python to handle errors and
            exceptions. The code in try block runs when there is no error. If
            the try block catches the error, then the except block is
            executed.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        try:
        num = int(input("Enter an integer: "))
    except ValueError:
        print("Number entered is not an integer.")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Enter an integer: 6.022
        Number entered is not an integer.
    </code>
    </pre>
          <br />
          <br />
          <h4>Output 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Enter an integer: -8.5
        Number entered is not an integer.
    </code>
    </pre>
          <br />
          <br />
          <h4>Output 3:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Enter an integer: -36
    </code>
    </pre>
          <br />
          <br />
          <p>
            In addition to try and except blocks, we also have else and
            finally blocks.
            <br />
            The code in else block is executed when there is no error in try
            block.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        try:
        num = int(input("Enter an integer: "))
    except ValueError:
        print("Number entered is not an integer.")
    else:
        print("Integer Accepted.")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Enter an integer: 69
        Integer Accepted.
    </code>
    </pre>
          <br />
          <br />
          <h4>Output 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Enter an integer: -2.3
        Number entered is not an integer.
    </code>
    </pre>
          <br />
          <br />
          <p>
            The finally block is execute whatever is the outcome of
            try……except…..else blocks.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        try:
        num = int(input("Enter an integer: "))
    except ValueError:
        print("Number entered is not an integer.")
    else:
        print("Integer Accepted.")
    finally:
        print("This block is always executed.")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output 1:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Enter an integer: 19
        Integer Accepted.
        This block is always executed.
    </code>
    </pre>
          <br />
          <br />
          <h4>Output 2:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
         Enter an integer: 3.142
         Number entered is not an integer.
         This block is always executed.
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div56" style="display: none">
          <h2>Python PIP</h2>
          <br />
          <p>
            pip stands for Package Installer for Python. It is used to install
            and manage software packages in python that are not the part of
            standard python library.
            <br />
            In the later versions of python (3.4 and after), the pip command
            is pre-installed.
          </p>
          <br />
          <br />
          <p>
            <b>To Check if pip is installed in your system, type the following
              in command prompt:</b>
          </p>
          <br />
          <li>pip --version</li>
          <br />
          <pre class="highlight">
    <code class="language-js">
        pip 22.2 from C:\users\yourName\appdata\local\programs\python\python39\lib\site-packages\pip (python 3.9)
    </code>
    </pre>
          <br />
          <br />
          <p>
            If your system does not have pip installed, you can easily
            download it from their official website:
            https://pypi.org/project/pip/
            <br />
            Now that pip has been installed in our system, we can download
            packages in system.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        PS D: \Python\Codes> pip install numpy  
        Collecting numpy
          Downloading numpy-1.23.1-cp39-cp39-win_amd64.whl (14.7 MB)
             ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 14.7/14.7 MB 2.9 MB/s eta 0:00:00
        Installing collected packages: numpy        
    </code>
    </pre>
          <br />
          <br />
          <p>
            If the package already exists then the following message is
            displayed:
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        PS D:\Python\Codes> pip install sklearn
        Requirement already satisfied: sklearn in c:\users\yourName\appdata\local\programs\python\python39\lib\site-packages (0.0)            
    </code>
    </pre>
          <br />
          <br />
          <p>To list all the installed packages:</p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        PS D:\Python\Codes> pip list
        Package                           Version
        --------------------------------- -------------------
        Flask                             2.0.3
        ipython                           8.0.1
        jupyter                           1.0.0
        keras                             2.8.0
        Kivy                              2.0.0
        matplotlib                        3.4.3
        mysql-connector                   2.2.9
        numpy                             1.19.5
        pandas                            1.4.1
        pip                               22.2
        plotly                            5.6.0
        pygame                            2.0.0
        scipy                             1.7.1
        seaborn                           0.11.2
        selenium                          3.141.0
        sklearn                           0.0
        sympy                             1.10
        tensorflow                        2.8.0                 
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div57" style="display: none">
          <h2>Data & Time</h2>
          <br />
          <p>
            Dates and timings are very important for computers. Computers
            keeps tracks of date and time for files, documents and various
            other operations. Similarly python uses date and time to perform
            several operations.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import time
        print(time.time())
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        1658659152.7263992
    </code>
    </pre>
          <br />
          <br />
          <p>
            So, what can we understand from the about output? What does a
            bunch of random numbers mean?
            <br />
            <b>These numbers are nothing but the number of ticks since the
              start of January 1, 1970 also called as epoch.</b>
            <br />
            Now, one might ask what are ticks?
            <br />
            <b>Ticks are floating point numbers measured in units of seconds
              for time interval.</b>
          </p>
          <br />
          <br />
          <p>
            We can also pass the epoch inside the ctime() function (or simply
            use the ctime() function) to print the current time in human
            readable format.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import time
        print(time.time())
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Sun Jul 24 16:24:50 2022
    </code>
    </pre>
          <br />
          <br />
          <h3>time.sleep()</h3>
          <br />
          <p>
            the sleep() function inside time module is used to delay execution
            of current time thread by the given number of seconds.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import time

        time.sleep(10)
        print(time.ctime())
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Sun Jul 24 16:24:50 2022
    </code>
    </pre>
          <br />
          <br />
          <p>
            As we can see, the sleep() will delay the execution 10 seconds.
          </p>
          <br />
          <h3>Time.struct_time_class:</h3>
          <br />
          <table>
            <tr>
              <th>Index</th>
              <th>Field</th>
              <th>Attribute</th>
              <th>Value</th>
              <th>Meaning</th>
              <th>Format codes</th>
            </tr>
            <tr>
              <td>0</td>
              <td>Year</td>
              <td>tm_year</td>
              <td>0000, ........, 9999</td>
              <td>Four digit year</td>
              <td>%Y</td>
            </tr>
            <tr>
              <td>1</td>
              <td>Month</td>
              <td>tm_mon</td>
              <td>1 - january, 2 - February, ......., 12 - December</td>
              <td>Months in a year</td>
              <td>%m</td>
            </tr>
            <tr>
              <td>2</td>
              <td>Day</td>
              <td>tm_mday</td>
              <td>1,2,3, ........, 29, 31</td>
              <td>Days in a month</td>
              <td>%d</td>
            </tr>
            <tr>
              <td>3</td>
              <td>Hour</td>
              <td>tm_hour</td>
              <td>0,1,2, ........, 22, 23</td>
              <td>Hours in a day</td>
              <td>%H</td>
            </tr>
            <tr>
              <td>4</td>
              <td>Minute</td>
              <td>tm_min</td>
              <td>0,1,2 ........, 58, 59</td>
              <td>Minutes in an hourr</td>
              <td>%M</td>
            </tr>
            <tr>
              <td>5</td>
              <td>Second</td>
              <td>tm_sec</td>
              <td>0,1,2, ........, 60,61</td>
              <td>Seconds in a Minute</td>
              <td>%S</td>
            </tr>
            <tr>
              <td>6</td>
              <td>Day of week</td>
              <td>tm_wday</td>
              <td>0 - Monday, 1 - Tuesday ........, 6 - Sunday</td>
              <td>Days in a week</td>
              <td>%W</td>
            </tr>
            <tr>
              <td>7</td>
              <td>Day of Year</td>
              <td>tm_yday</td>
              <td>1,2,3, ........, 355, 356</td>
              <td>Days in a year</td>
              <td>%j</td>
            </tr>
            <tr>
              <td>8</td>
              <td>Daylighting savings</td>
              <td>tm_isdst</td>
              <td>-1,0,1</td>
            </tr>
          </table>
          <br />
          <br />
          <h3>time.localtime():</h3>
          <br />
          <p>
            To get the output of local time in struct_time format, use the
            localtime() function.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import time

        print(time.localtime(1658672956.8853111))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        time.struct_time(tm_year=2022, tm_mon=7, tm_mday=24, tm_hour=19, tm_min=59, tm_sec=16, tm_wday=6, tm_yday=205, tm_isdst=0)
    </code>
    </pre>
          <br />
          <br />
          <h3>time.gmtime():</h3>
          <br />
          <p>
            To get the output of Coordinated Universal Time in struct_time
            format, use the gmtime() function.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import time

        print(time.gmtime(1658672956.8853111))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        time.struct_time(tm_year=2022, tm_mon=7, tm_mday=24, tm_hour=14, tm_min=29, tm_sec=16, tm_wday=6, tm_yday=205, tm_isdst=0)
    </code>
    </pre>
          <br />
          <br />
          <h3>time.mktime():</h3>
          <br />
          <p>
            We also have the reverse of localtime() function that prints
            seconds passed since epoch in local time.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import time

        local_time = (2022, 7, 24, 20, 14, 39, 6, 205, 0)
        print(time.mktime(local_time))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        1658673879.0
    </code>
    </pre>
          <br />
          <br />
          <h3>time.asctime():</h3>
          <br />
          <p>
            The asctime() function takes struct_time and prints a single
            string representing it.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import time

        local_time = (2022, 7, 24, 20, 14, 39, 6, 205, 0)
        print(time.asctime(local_time))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Sun Jul 24 20:14:39 2022
    </code>
    </pre>
          <br />
          <br />
          <h3>time.strptime():</h3>
          <br />
          <p>
            This function parses string based on given format and returns it
            in struct_time format.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import time

        local_time = "24 July, 2022"
        print(time.strptime(local_time, "%d %B, %Y"))
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        time.struct_time(tm_year=2018, tm_mon=7, tm_mday=24, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=1, tm_yday=205, tm_isdst=-1)
    </code>
    </pre>
          <br />
          <br />
          <h3>Calendar:</h3>
          <br />
          <p>
            We can even print a calendar for a particular month. This can be
            done using the calendar module.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        import calendar

        print(calendar.month(2022, 7)) 
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        July 2022
        Mo Tu We Th Fr Sa Su
                1   2   3  4       
        5    6    7   8   9  10
        11  12  13 14  15 16 17
        18  19  20 21  22 23 24
        25  26  27 28  29 30 31        
    </code>
    </pre>
          <br />
          <br />
        </div>
        <div class="notes" id="div58" style="display: none">
          <h2>Python File Handling</h2>
          <br />
          <p>
            File handling in python lets you open, read, write, append, modify
            files.
            <br />
            <b>Note: For the sake of this tutorial, we will assume that your
              text file and python code are present in the same directory.</b>
            <br />
            Before we perform any operation on file, we need to open the file.
            This is done using the open() function.
          </p>
          <br />
          <br />
          <p>
            Example: lets say we have a text file (someText.txt) with some
            content in it. The open() function creates a file object with
            read() method for reading the content.
          </p>
          <br />
          <pre class="highlight">
    <code class="language-js">
        file = open("someText.txt")
        print(file.read()) 
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        lorem ipsum

        In publishing and graphic design, Lorem ipsum is a placeholder text commonly used to demonstrate the visual form of a document or a typeface without relying on meaningful content.               
    </code>
    </pre>
          <br />
          <br />
          <p>There are various modes in which we can open files.</p>
          <br />
          <li>
            read (r): This mode opens the file for reading only and gives an
            error if the file does not exist. This is the default mode if no
            mode is passed as a parameter.
          </li>
          <li>
            write (w): This mode opens the file for writing only and creates a
            new file if the file does not exist.
          </li>
          <li>
            append (a): This mode opens the file for appending only and
            creates a new file if the file does not exist.
          </li>
          <li>
            create (x): This mode creates a file and gives an error if the
            file already exists.
          </li>
          <br />
          <br />
          <p>
            Apart from these modes we also need to specify how the file must
            be handled:
          </p>
          <br />
          <li>text (t): Used to handle text files.</li>
          <li>binary (b): used to handle binary files (images).</li>
          <br />
          <br />
        </div>
        <div class="notes" id="div59" style="display: none">
          <h2>Read/Write Files</h2>
          <br />
          <h3>A. Create a File:</h3>
          <br />
          <p>Creating a file is primarily done using the create (x) mode.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        file = open("Text.txt", "x")
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        A file named Text.txt is created with no content.      
    </code>
    </pre>
          <br />
          <br />
          <h3>B. Write onto a File:</h3>
          <br />
          <p>This method writes content onto a file.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        file = open("Text.txt", "w")
        file.write("This is an example of file creation.")
        file.close
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        This is an example of file creation.   
    </code>
    </pre>
          <br />
          <br />
          <p>
            If the file already exists with some content of its own, then this
            mode overwrites it.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        file = open("Text.txt", "w")
        file.write("This is overwritten text.")
        file.close
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        This is overwritten text.   
    </code>
    </pre>
          <br />
          <br />
          <h3>C. Read a File:</h3>
          <br />
          <p>This method allows us to read the contents of the file.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        file = open("Text2.txt", "r")
        print(file.read())
        file.close
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        Hello, I’m a Potato. 
    </code>
    </pre>
          <br />
          <br />
          <h3>D. Append a File:</h3>
          <br />
          <p>This method appends content into a file.</p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        file = open("newText.txt", "a")
        file.write("This is an example of file appending.")
        file.close
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        This is an example of file appending.
    </code>
    </pre>
          <br />
          <br />
          <p>
            However, If the file exists already with some content in it, then
            the new content gets appended.
          </p>
          <br />
          <h4>Example:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        file = open("newText.txt", "a")
        file.write(" Hello, I'm appending")
        file.close
    </code>
    </pre>
          <br />
          <br />
          <h4>Output:</h4>
          <br />
          <pre class="highlight">
    <code class="language-js">
        This is an example of file appending. Hello, I'm appending
    </code>
    </pre>
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          <br />
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