public static void OnClickSub(this UIBehaviour ui, Action <PointerEventData> action)
 {
     ui
     .OnPointerClickAsObservable()
     .Subscribe(_ => action(_))
     .AddTo(ui);
 }
 public override IObservable <Unit> OnFulfilledAsObservable()
 {
     return(UIBehaviour.OnPointerClickAsObservable().AsUnitObservable());
 }