adding in list pandas code example

Example 1: python add to list

list_to_add.append(item_to_add)

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]