itertools.groupby turns [A] | [B] into [A | B]

[shenriotpro]

Hi, hope this snippet helps, runs fine, but ty complains
Expected Iterator[str] | Iterator[int], found Iterator[str | int]

from itertools import groupby
from typing import Sequence, Iterator


def group(items: Sequence[str] | Sequence[int]):
    for key, group in groupby(items):
        f(group)
    

def f(items: Iterator[str] | Iterator[int]):
    print(list(items))


group(["a", "b", "c"])
group([1, 2, 3])

[srittau]

The problem here is that type checkers infer type groupby(items) to have type groupby[str | int, str | int] (or groupy[object] in mypy's case), when really they should infer type groupby[int, int] | groupby[str, str].

I don't think this is something that can be solved in typeshed.

[shenriotpro]

Thanks for taking a look