Permutations algorythm implementation.

permutations.py

def permutations(l):
    """
    >>> f = permutations
    >>> f(['a', 'b'])
    [('a', 'b'), ('b', 'a')]
    >>> f(['a', 'b', 'c'])
    [('a', 'b', 'c'), ('a', 'c', 'b'), ('b', 'a', 'c'), ('b', 'c', 'a'), ('c', 'a', 'b'), ('c', 'b', 'a')]
    """
    
    if len(l) == 1:
        return [(l[0],)]
    else:
        ret = []
        for i, item in enumerate(l):
            others = l[:i] + l[i + 1:]
            for p in permutations(others):
                ret.append((item,) + p)
        return ret