code: func (sw *Switch) OnStart() error {
  	sw.BaseService.OnStart()
  	// Start reactors
  	for _, reactor := range sw.reactors {
  		_, err := reactor.Start()
  		if err != nil {
  			return err
  		}
  	}
  	// Start peers
  	for _, peer := range sw.peers.List() {
  		sw.startInitPeer(peer)
  	}
  	// Start listeners
  	for _, listener := range sw.listeners {
  		go sw.listenerRoutine(listener)
  	}
  	return nil
  }
docs: // Switch.Start() starts all the reactors, peers, and listeners.