code: def _sendRequest(self, tReq):
          
          try:
              tReq.sent = True
              self.proto.sendString(tReq.data)
          except Exception as e:
              log.exception('%r: Failed to send request %r', self, tReq)
              del self.requests[tReq.id]
              tReq.d.errback(e)
          else:
              if not tReq.expect:
                  # Once we've sent a request for which we don't expect a reply,
                  # we're done, remove it from requests, and fire the deferred
                  # with 'None', since there is no reply to be expected
                  del self.requests[tReq.id]
                  tReq.d.callback(None)
docs: Send a single request over our protocol to the Kafka broker.