code: func (e *eventer) On(n string, f func(s interface{})) (err error) {
  	out := e.Subscribe()
  	go func() {
  		for {
  			select {
  			case evt := <-out:
  				if evt.Name == n {
  					f(evt.Data)
  				}
  			}
  		}
  	}()
  
  	return
  }
docs: // On executes the event handler f when e is Published to.