append at an index in python code example

Example 1: append to lists python

list = []          ## Start as the empty list
  list.append('a')   ## Use append() to add elements
  list.append('b')

Example 2: append to lists python

list = [1, 2, 3]
  print list.append(4)   ## NO, does not work, append() returns None
  ## Correct pattern:
  list.append(4)
  print list  ## [1, 2, 3, 4]