#!/usr/bin/python3

from collections.abc import Iterable
from typing import cast


def unproblematic(iter: Iterable[int]) -> None:
    print(iter)


def problematic(iter: Iterable[int | str]) -> None:
    print(iter)


def key(item: int) -> int:
    return -item


def main() -> None:
    items: list[int] = [3, 4, 1, 2]

    unproblematic(sorted(items, key=key))  # Works.
    problematic(sorted(items, key=key))  # Fails mypy arg-type.

    workaround = sorted(items, key=key)
    problematic(workaround)  # Works.

    problematic(cast(Iterable[int], sorted(items, key=key)))  # Works.


if __name__ == '__main__':
    main()