Atbash.py: Both raw_input() and unichr() were removed in Python 3 (TheAlgorithms#855)

* Atbash.py: Both raw_input() and unichr() were removed in Python 3

@sateslayer and @AnupKumarPanwar your reviews please.

* Remove any leading / trailing whitespace from user input

Author: cclauss

ciphers/Atbash.py

@@ -1,14 +1,21 @@
+try:               # Python 2
+    raw_input
+    unichr
+except NameError:  # Python 3
+    raw_input = input
+    unichr = chr
+
+
 def Atbash():
-    inp=raw_input("Enter the sentence to be encrypted  ")
     output=""
-    for i in inp:
-        extract=ord(i)
-        if extract>=65 and extract<=90:
-            output+=(unichr(155-extract))
-        elif extract>=97 and extract<=122:
-            output+=(unichr(219-extract))
+    for i in raw_input("Enter the sentence to be encrypted ").strip():
+        extract = ord(i)
+        if 65 <= extract <= 90:
+            output += unichr(155-extract)
+        elif 97 <= extract <= 122:
+            output += unichr(219-extract)
         else:
             output+=i
-    print (output)
+    print(output)
 
-Atbash()   ;
+Atbash()