code: def Heartbeat(self):
      
      heartbeat_msg = common_pb2.Message(
          message_type="Heartbeat",
          destination=common_pb2.Address(service_name="system"))
      self._SendImpl(heartbeat_msg)
docs: Sends a heartbeat to the Fleetspeak client.
  
      If this daemonservice is configured to use heartbeats, clients that don't
      call this method often enough are considered faulty and are restarted by
      Fleetspeak.