code: func (g *Gui) handleEvent(ev *termbox.Event) error {
  	switch ev.Type {
  	case termbox.EventKey, termbox.EventMouse:
  		return g.onKey(ev)
  	case termbox.EventError:
  		return ev.Err
  	default:
  		return nil
  	}
  }
docs: // handleEvent handles an event, based on its type (key-press, error,
  // etc.)