code: func (s *Server) Stop() {
  	if s.serverStopChan == nil {
  		panic("gorpc.Server: server must be started before stopping it")
  	}
  	close(s.serverStopChan)
  	s.stopWg.Wait()
  	s.serverStopChan = nil
  }
docs: // Stop stops rpc server. Stopped server can be started again.