from typing import Iterator
from typing import Tuple
from typing import Any
import itertools


def _nonnull_powerset(iterable) -> Iterator[Tuple[Any]]:
    """Returns powerset of iterable, minus the empty set."""
    s = list(iterable)
    return itertools.chain.from_iterable(
        itertools.combinations(s, r) for r in range(1, len(s) + 1))