from itertools import chain, combinations

def powerset(s):
    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))

for result in powerset(range(3)):
    print(result)