# but stop waiting if the done event is set
            done, other = await asyncio.wait(
                [
                    # NOTE: If you add other tasks here, update the code below,
                    # which assumes each set has exactly one task each
                    asyncio.ensure_future(self.queue.get()),
                    asyncio.ensure_future(self.done.wait()),
                ],
                return_when=asyncio.FIRST_COMPLETED,
            )
            # Cancel the other task
            if other:
                other.pop().cancel()
            # Extract the value of the first completed task
            token_or_done = cast(Union[str, Literal[True]], done.pop().result())
            # If the extracted value is the boolean True, the done event was set
            if token_or_done is True:
                break
            # Otherwise, the extracted value is a token, which we yield
            yield token_or_done