def _wait_for_json_responses(self, num_responses=1):
        if not self.resp_queue:
            # Source is not actually expecting a response
            return
        responses = []
        wait_time = CONF.cells.call_timeout
        try:
            for x in range(num_responses):
                json_responses = self.resp_queue.get(timeout=wait_time)
                responses.extend(json_responses)
        except queue.Empty:
            raise exception.CellTimeout()
        finally:
            self._cleanup_response_queue()
        return responses
Wait for response(s) to be put into the eventlet queue.  Since
dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/cells/messaging.py/_BaseMessage._wait_for_json_responses