code: def start(self):
          
          with self._operational_lock:
              if self._thread is not None:
                  raise ValueError("Dispatcher is already running.")
  
              flow_control = self._manager.flow_control
              worker = helper_threads.QueueCallbackWorker(
                  self._queue,
                  self.dispatch_callback,
                  max_items=flow_control.max_request_batch_size,
                  max_latency=flow_control.max_request_batch_latency,
              )
              # Create and start the helper thread.
              thread = threading.Thread(name=_CALLBACK_WORKER_NAME, target=worker)
              thread.daemon = True
              thread.start()
              _LOGGER.debug("Started helper thread %s", thread.name)
              self._thread = thread
docs: Start a thread to dispatch requests queued up by callbacks.
          Spawns a thread to run :meth:`dispatch_callback`.