concurrent.futures: fix top level available objects, add InvalidStateError (#4021)

* concurrent.futures: add InvalidStateError

* concurrent.futures: fix package imports

* asyncio.futures: fix import

* concurrent.futures: fix version availability for BrokenExecutor

* concurrent.futures: make consistent

* concurrent.futures: update whitelist

Co-authored-by: hauntsaninja <>

stdlib/3/asyncio/futures.pyi

@@ -1,7 +1,7 @@
 import sys
 from typing import Any, Union, Callable, TypeVar, Type, List, Iterable, Generator, Awaitable, Optional, Tuple
 from .events import AbstractEventLoop
-from concurrent.futures import (
+from concurrent.futures._base import (
     Future as _ConcurrentFuture,
     Error,
 )