Union(Type) and TypeForm

My function should analyze types.
Both when --warn-unreachable is enabled, and when checking typing.Union, and when checking types.UnionType, an error occurs.

code:

from types import UnionType
from typing import Any, Union

from typing_extensions import TypeForm


def f(t: TypeForm[Any]) -> Any:
    if isinstance(t, Union):
        pass


def g(t: TypeForm[Any]) -> Any:
    if isinstance(t, UnionType):
        pass

errors:

main.py:8: error: Argument 2 to "isinstance" has incompatible type "<typing special form>"; expected "_ClassInfo"  [arg-type]
main.py:14: error: Statement is unreachable  [unreachable]
Found 2 errors in 1 file (checked 1 source file)

in runtime, the behavior of both isinstance is equivalent.

Empieza reproduciendo el ejemplo de main.py con mypy, con y sin --warn-unreachable, e inspecciona cómo se gestionan typing.Union y types.UnionType cuando el valor está anotado con typing_extensions.TypeForm. Se considerará terminado cuando las comprobaciones isinstance equivalentes ya no produzcan los errores notificados de tipo incompatible o de sentencia inalcanzable.