Shared via mypy Playground

main.py

from typing import Type
from typing import Any
from typing import TypeVar
from typing import cast

T = TypeVar("T")

def assert_type(x: Any, type: Type[T]) -> None:
    if not isinstance(x, type):
        raise TypeError()
    return None

def func(x: str) -> str:
    return x

unbound: object
assert_type(unbound, str)
func(cast(str, unbound))

bound: str
assert_type(bound, str)
func(cast(str, bound))
func(bound)  # type: ignore