Mark asyncio loop parameters as Optional (#3047)

stdlib/3/asyncio/tasks.pyi

@@ -21,42 +21,42 @@ FIRST_EXCEPTION: str
 FIRST_COMPLETED: str
 ALL_COMPLETED: str
 
-def as_completed(fs: Sequence[_FutureT[_T]], *, loop: AbstractEventLoop = ...,
+def as_completed(fs: Sequence[_FutureT[_T]], *, loop: Optional[AbstractEventLoop] = ...,
                  timeout: Optional[float] = ...) -> Iterator[Future[_T]]: ...
 def ensure_future(coro_or_future: _FutureT[_T],
                   *, loop: Optional[AbstractEventLoop] = ...) -> Future[_T]: ...
 # Prior to Python 3.7 'async' was an alias for 'ensure_future'.
 # It became a keyword in 3.7.
 @overload
 def gather(coro_or_future1: _FutureT[_T1],
-           *, loop: AbstractEventLoop = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1]]: ...
+           *, loop: Optional[AbstractEventLoop] = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1]]: ...
 @overload
 def gather(coro_or_future1: _FutureT[_T1], coro_or_future2: _FutureT[_T2],
-           *, loop: AbstractEventLoop = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1, _T2]]: ...
+           *, loop: Optional[AbstractEventLoop] = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1, _T2]]: ...
 @overload
 def gather(coro_or_future1: _FutureT[_T1], coro_or_future2: _FutureT[_T2], coro_or_future3: _FutureT[_T3],
-           *, loop: AbstractEventLoop = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1, _T2, _T3]]: ...
+           *, loop: Optional[AbstractEventLoop] = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1, _T2, _T3]]: ...
 @overload
 def gather(coro_or_future1: _FutureT[_T1], coro_or_future2: _FutureT[_T2], coro_or_future3: _FutureT[_T3],
            coro_or_future4: _FutureT[_T4],
-           *, loop: AbstractEventLoop = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1, _T2, _T3, _T4]]: ...
+           *, loop: Optional[AbstractEventLoop] = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1, _T2, _T3, _T4]]: ...
 @overload
 def gather(coro_or_future1: _FutureT[_T1], coro_or_future2: _FutureT[_T2], coro_or_future3: _FutureT[_T3],
            coro_or_future4: _FutureT[_T4], coro_or_future5: _FutureT[_T5],
-           *, loop: AbstractEventLoop = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1, _T2, _T3, _T4, _T5]]: ...
+           *, loop: Optional[AbstractEventLoop] = ..., return_exceptions: bool = ...) -> Future[Tuple[_T1, _T2, _T3, _T4, _T5]]: ...
 @overload
 def gather(coro_or_future1: _FutureT[Any], coro_or_future2: _FutureT[Any], coro_or_future3: _FutureT[Any],
            coro_or_future4: _FutureT[Any], coro_or_future5: _FutureT[Any], coro_or_future6: _FutureT[Any],
            *coros_or_futures: _FutureT[Any],
-           loop: AbstractEventLoop = ..., return_exceptions: bool = ...) -> Future[Tuple[Any, ...]]: ...
+           loop: Optional[AbstractEventLoop] = ..., return_exceptions: bool = ...) -> Future[Tuple[Any, ...]]: ...
 def run_coroutine_threadsafe(coro: _FutureT[_T],
                              loop: AbstractEventLoop) -> concurrent.futures.Future[_T]: ...
-def shield(arg: _FutureT[_T], *, loop: AbstractEventLoop = ...) -> Future[_T]: ...
-def sleep(delay: float, result: _T = ..., loop: AbstractEventLoop = ...) -> Future[_T]: ...
-def wait(fs: Iterable[_FutureT[_T]], *, loop: AbstractEventLoop = ..., timeout: Optional[float] = ...,
+def shield(arg: _FutureT[_T], *, loop: Optional[AbstractEventLoop] = ...) -> Future[_T]: ...
+def sleep(delay: float, result: _T = ..., loop: Optional[AbstractEventLoop] = ...) -> Future[_T]: ...
+def wait(fs: Iterable[_FutureT[_T]], *, loop: Optional[AbstractEventLoop] = ..., timeout: Optional[float] = ...,
          return_when: str = ...) -> Future[Tuple[Set[Future[_T]], Set[Future[_T]]]]: ...
 def wait_for(fut: _FutureT[_T], timeout: Optional[float],
-             *, loop: AbstractEventLoop = ...) -> Future[_T]: ...
+             *, loop: Optional[AbstractEventLoop] = ...) -> Future[_T]: ...
 
 class Task(Future[_T], Generic[_T]):
     @classmethod