Added generic example of std::ops::Add in doc comments

Added blank lines around example

Added comment to Add example referencing the Output type

Removed whitespace from lines 272 and 273

Removed Debug derivation from Add examples

Added Debug derivation

Author: mandeep

src/libcore/ops.rs

@@ -235,6 +235,42 @@ pub trait Drop {
 /// }
 /// ```
 ///
+/// Here is an example of the same `Point` struct implementing the `Add` trait
+/// using generics.
+///
+/// ```
+/// use std::ops::Add;
+///
+/// #[derive(Debug)]
+/// struct Point<T> {
+///     x: T,
+///     y: T,
+/// }
+///
+/// // Notice that the implementation uses the `Output` associated type
+/// impl<T: Add<Output=T>> Add for Point<T> {
+///     type Output = Point<T>;
+///
+///     fn add(self, other: Point<T>) -> Point<T> {
+///         Point {
+///             x: self.x + other.x,
+///             y: self.y + other.y,
+///         }
+///     }
+/// }
+///
+/// impl<T: PartialEq> PartialEq for Point<T> {
+///     fn eq(&self, other: &Self) -> bool {
+///         self.x == other.x && self.y == other.y
+///     }
+/// }
+///
+/// fn main() {
+///     assert_eq!(Point { x: 1, y: 0 } + Point { x: 2, y: 3 },
+///                Point { x: 3, y: 3 });
+/// }
+/// ```
+///
 /// Note that `RHS = Self` by default, but this is not mandatory. For example,
 /// [std::time::SystemTime] implements `Add<Duration>`, which permits
 /// operations of the form `SystemTime = SystemTime + Duration`.