from typing import Any, List, Iterator, Dict, Union


def from_str(x: Any) -> str:
    assert isinstance(x, str)
    return x


def from_bool(x: Any) -> bool:
    assert isinstance(x, bool)
    return x


def from_int(x: Any) -> int:
    assert isinstance(x, int) and not isinstance(x, bool)
    return x
