from __future__ import annotations

from typing import TypeVar, Generic, Union, overload

T = TypeVar("T", int, str)


class Series(Generic[T]):
    @overload
    def __new__(cls, dtype: int) -> IntSeries:
        ...

    @overload
    def __new__(cls, dtype: type[T]) -> Series[T]:
        ...

    @overload
    def __new__(cls, dtype=...) -> Series:
        ...

    def __new__(cls, dtype=...) -> Series:
        cls.dtype = dtype
        return object.__new__(cls)

    ...


class IntSeries(Series[int]):
    ...


class Index:
    @overload
    def __new__(cls, dtype: int) -> IntIndex:
        ...

    @overload
    def __new__(cls, dtype=...) -> Index:
        ...

    def __new__(cls, dtype=...) -> Index:
        cls.dtype = dtype
        return object.__new__(cls)


class IntIndex(Index):
    ...


def foo(x: Union[Series, int, Index]):
    if isinstance(x, (Series, Index)):
        reveal_type(x)
    else:
        reveal_type(x)