Power Set

def print_powerset(a):
    l = len(a)
    r = range(l)
    b = [0] * l

    while True:
        print([a[x] for x in r if b[x]])

        i = 0
        while True:
            if b[i] == 0:
                b[i] = 1
                break

            b[i] = 0
            i += 1

            if i == l:
                return

print_powerset([1, 2, 3, 4, 5])