Suppose I have:

from typing import Any, TypeVar

import numpy as np


T = TypeVar("T")
U = TypeVar("U")
ListLike = T | list[T] | tuple[T, ...] | np.ndarray[Any, U]
ListLikeStr = ListLike[str, np.object_]
# ListLikeStr should be: str | list[str] | tuple[str, ...] | np.ndarray[Any, np.object_]

This works, but it was lucky. I could have instead written: ListLike[np.object_, str], and then I’d get ListLikeStr being np.object_ | list[np.object_] | tuple[np.object_, ...] | np.ndarray[Any, str], which is not what I’d like.

Ideally I could have done something like: ListLike[T=str, U=np.object_], but that does not work. So what determines the order when I am instantiating the type variables in ListLike? How does ListLike “know” that T corresponds with str and U with np.object_, when I write ListLike[str, np.object_]?