gen.py 文件源码

def next(self):
        """Returns a `.Future` that will yield the next available result.

        Note that this `.Future` will not be the same object as any of
        the inputs.
        """
        self._running_future = TracebackFuture()

        if self._finished:
            self._return_result(self._finished.popleft())

        return self._running_future