Clean up the example on slice::IterMut::as_slice()

Author: cuviper

src/libcore/slice/mod.rs

@@ -3300,20 +3300,16 @@ impl<'a, T> IterMut<'a, T> {
     ///
     /// ```
     /// # #![feature(slice_iter_mut_as_slice)]
-    /// // First, we declare a type which has `iter_mut` method to get the `IterMut`
-    /// // struct (&[usize here]):
     /// let mut slice: &mut [usize] = &mut [1, 2, 3];
     ///
-    /// // Then, we get the iterator:
+    /// // First, we get the iterator:
     /// let mut iter = slice.iter_mut();
-    /// // So if we print what the `as_slice` method returns here, we have "[1, 2, 3]":
-    /// println!("{:?}", iter.as_slice());
+    /// // So if we check what the `as_slice` method returns here, we have "[1, 2, 3]":
     /// assert_eq!(iter.as_slice(), &[1, 2, 3]);
     ///
     /// // Next, we move to the second element of the slice:
     /// iter.next();
     /// // Now `as_slice` returns "[2, 3]":
-    /// println!("{:?}", iter.as_slice());
     /// assert_eq!(iter.as_slice(), &[2, 3]);
     /// ```
     #[unstable(feature = "slice_iter_mut_as_slice", reason = "recently added", issue = "0")]