Need type hint for `getattr`

从提供的 CallBatch 和 Callbacks 示例开始，重点关注 CallBatch.getattr 以及所请求的通用 getattr 行为。按照 issue 中的描述，当 get_x 和 get_y 调用能够展示出会随访问的属性名称而变化的推断 callback 类型时，即视为完成。

from __future__ import annotations

from typing import Callable, Generator, LiteralString, Self, Tuple


class Callbacks[**P, T]:
    def __init__(self, funcs: Generator[Callable[P, T]]):
        self.funcs = funcs

    def __call__(self, *args: P.args, **kwargs: P.kwargs):
        return [func(*args, **kwargs) for func in self.funcs]


class CallBatch[T]:
    def __init__(self, objs: Generator[T]):
        self.objs = objs

    def __getattr__[ITEM:LiteralString](self, item:ITEM):
        return Callbacks(getattr(obj, item) for obj in self.objs)


class A:
    instances_pool = dict[str, Self]()

    @classmethod
    def get(cls, x: str, y: int):
        id = cls.get_id(x, y)
        if id in cls.instances_pool:
            return cls.instances_pool[id]
        return cls(x, y)

    @classmethod
    def get_id(cls, x: str, y: int):
        return f"{x}_{y}"

    @classmethod
    def call_batch(cls, *xy: Tuple[str, int]):
        return CallBatch[Self](cls.get(x, y) for x, y in xy)

    def __init__(self, x: str, y: int):
        self.x = x
        self.y = y
        self.id = self.get_id(x, y)
        self.instances_pool[self.id] = self

    def get_x(self):
        return self.x

    def get_y(self):
        return self.y


x = A.call_batch(("1", 1), ("2", 2)).get_x()
x = A.call_batch(("1", 1), ("2", 2)).get_y()

I want type inference for Callbacks.
To achieve this, abilities blow should be support:

1. CallBatch/__getattr__/item can be marked as type of attributes types of T(may be a LiteralString)
2. getattr should have two generic types, one is type of object, the other is type of input name, and change return type when input name changes