PEP 484 says that @overload is only allowed in stubs.

But if I have a function like this:

    def plus1(x):
        return x + 1

then the most precise type is an overload:

    def plus1(x: int) -> int
    def plus1(x: float) -> float
    def plus1(x: complex) -> complex

This particular case could, of course, be handled by

    Number = TypeVar('Number', int, float, complex)
    def f(x: Number) -> Number

But I can easily construct other examples that can't be solved by type variables.

I don't think that @overload requires any additional dispatch machinery in Python (despite what the PEP says) -- it merely describes what the function can do in a more precise way than this:

    def plus1(x: Union[int,float,complex]) -> Union[int,float,complex]