Permutation and Composition Algorithm using Iterator in Python

PermandComp.py

def PermutationEnumerator(items, n=None):
    if n is None:
        n = len(items)
    for i in range(len(items)):
        v = items[i:i+1]
        if n == 1:
            yield v
        else:
            rest = items[:i] + items[i+1:]
            for p in PermutationEnumerator(rest, n-1):
                yield v + p

def CombinationEnumerator(items, n=None):
    if n is None:
        n = len(items)
    for i in range(len(items)):
        v = items[i:i+1]
        if n == 1:
            yield v
        else:
            rest = items[i+1:]
            for c in CombinationEnumerator(rest, n-1):
                yield v + c
               
if __name__ == "__main__" :
    items = [ 'a', 'b', 'c','d','e']
    for selection in range(1, len(items)) :
        enum = CombinationEnumerator(items, selection)
        for i in enum :
            print i
    print items