Python Knuth shuffle algorithm

gistfile1.py

def knuth_shuffle(items):
    """
    Fisher-Yates shuffle or Knuth shuffle which name is more famous.
    See <http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle> for detail
    Type : [a] -> None (shuffle inplace)
    Post constrain: Should be list 
    Post constrain: return array of the same length of input
    """

    for i in range(len(items)):
        j = randrange(i, len(items))
        items[i], items[j] = items[j], items[i]