private void OnButton3Clicked(object sender, EventArgs e)
        {
            Button button = (Button)sender;

            Xamarin.Forms.Animation parentAnimation = new Xamarin.Forms.Animation();

            Xamarin.Forms.Animation upAnimation = new Xamarin.Forms.Animation(v => button.Scale = v, 1, 5, Easing.SpringIn, () => Debug.WriteLine("up finished"));

            parentAnimation.Add(0, 0.5, upAnimation);

            Xamarin.Forms.Animation downAnimation = new Xamarin.Forms.Animation(v => button.Scale = v, 5, 1, Easing.SpringOut, () => Debug.WriteLine("down finished"));

            parentAnimation.Insert(0.5, 1, downAnimation);

            parentAnimation.Commit(this, "Animation3", 16, 5000, null, (v, c) => Debug.WriteLine("parent finished: {0} {1}", v, c));
        }