code: func NewController(ps *pss.Pss) *Controller {
  	ctrl := &Controller{
  		pss:           ps,
  		notifiers:     make(map[string]*notifier),
  		subscriptions: make(map[string]*subscription),
  	}
  	ctrl.pss.Register(&controlTopic, pss.NewHandler(ctrl.Handler))
  	return ctrl
  }
docs: // NewController creates a new Controller object