async def __aexit__(self, exc_type, exc_val, exc_tb):
    (await self._exit_stack.__aexit__(exc_type, exc_val, exc_tb))
    del self._task_group
async def __aexit__(self, exc_type, exc_val, exc_tb):
    (await self._exit_stack.__aexit__(exc_type, exc_val, exc_tb))
    del self._task_group