[stdlib][asyncio] Accept optional context in (Timer)Handle (#4190)

stdlib/3/asyncio/events.pyi

@@ -8,6 +8,8 @@ from asyncio.protocols import BaseProtocol
 from asyncio.tasks import Task
 from asyncio.transports import BaseTransport
 from asyncio.unix_events import AbstractChildWatcher
+if sys.version_info >= (3, 7):
+    from contextvars import Context
 
 from _types import FileDescriptorLike
 
@@ -21,7 +23,10 @@ _TransProtPair = Tuple[BaseTransport, BaseProtocol]
 class Handle:
     _cancelled = False
     _args: Sequence[Any]
-    def __init__(self, callback: Callable[..., Any], args: Sequence[Any], loop: AbstractEventLoop) -> None: ...
+    if sys.version_info >= (3, 7):
+        def __init__(self, callback: Callable[..., Any], args: Sequence[Any], loop: AbstractEventLoop, context: Optional[Context] = ...) -> None: ...
+    else:
+        def __init__(self, callback: Callable[..., Any], args: Sequence[Any], loop: AbstractEventLoop) -> None: ...
     def __repr__(self) -> str: ...
     def cancel(self) -> None: ...
     def _run(self) -> None: ...
@@ -29,8 +34,12 @@ class Handle:
         def cancelled(self) -> bool: ...
 
 class TimerHandle(Handle):
-    def __init__(self, when: float, callback: Callable[..., Any], args: Sequence[Any],
-                 loop: AbstractEventLoop) -> None: ...
+    if sys.version_info >= (3, 7):
+        def __init__(self, when: float, callback: Callable[..., Any], args: Sequence[Any],
+                     loop: AbstractEventLoop, context: Optional[Context] = ...) -> None: ...
+    else:
+        def __init__(self, when: float, callback: Callable[..., Any], args: Sequence[Any],
+                     loop: AbstractEventLoop) -> None: ...
     def __hash__(self) -> int: ...
     if sys.version_info >= (3, 7):
         def when(self) -> float: ...