subset.py

def subset(head, tail=None):
    """Generate subsets."""

    if not head:
        return

    if tail is None:
        tail = []
        yield []

    head = head[:]
    while head:
        t = tail + [head.pop(0)]
        yield from subset(head, t)
        yield t

x = [1, 2, 3]
print(list(subset(x)))


def sub_set(head, tail=None):
    """Generate subsets."""

    if not head:
        return

    if tail is None:
        tail = set()
        yield tail

    head = head.copy()
    while head:
        t = tail.union({head.pop()})
        yield from (set(y) for y in sub_set(head, t))
        yield t


print(list(sub_set(x)))