docs: def send(self, request, blocking=True):
          """Queue request for async network send, return Future()"""
          future = Future()
          if self.connecting():
              return future.failure(Errors.NodeNotReadyError(str(self)))
          elif not self.connected():
              return future.failure(Errors.KafkaConnectionError(str(self)))
          elif not self.can_send_more():
              return future.failure(Errors.TooManyInFlightRequests(str(self)))
          return self._send(request, blocking=blocking)