from typing import Literal, overload

def check[T](actual: T) -> T: ...

class Kitten: ...
class Puppy: ...

@overload
def read_csv[S](
    filepath_or_buffer: str,
    *,
    iterator: Literal[True],
) -> Puppy: ...
@overload
def read_csv(
    filepath_or_buffer: str,
    *,
    iterator: Literal[False],
) -> Kitten: ...
def read_csv(*args, **kwargs) -> Puppy | Kitten: ...

def test_types_csv(path: str) -> None:
    check(read_csv(path, iterator=False))  # false positive: Argument `Kitten` is not assignable to parameter `actual` with type `Puppy` in function `check`