Rg.Plugins.Popup.Pages.PopupPage.ExecuteWhenAppearingOnce C# (CSharp) Method

        internal void ExecuteWhenAppearingOnce(Action action)
        {
            _appearingAction = action;
        }

 public static Task PushAsync(PopupPage page, bool animate = true)
 {
     var task = new TaskCompletionSource<bool>();
     if (animate)
     {
         page.PreparingAnimation();
         page.ExecuteWhenAppearingOnce(async () =>
         {
             await page.AppearingAnimation();
             task.TrySetResult(true);
         });
     }
     DependencyService.Get<IPopupNavigation>().AddPopup(page);
     _popupStack.Add(page);
     if (!animate) task.TrySetResult(true);
     return task.Task;
 }