public static void EnsureAnimator(UIElement targetElement, ref OpacityAnimator animator)
 {
     if (animator == null)
     {
         animator = new OpacityAnimator(targetElement);
     }
     if (animator == null)
     {
         throw new InvalidOperationException("The animation system could not be prepared for the target element.");
     }
 }
 public static void EnsureAnimator(UIElement targetElement, ref OpacityAnimator animator)
 {
     if (animator == null)
     {
         animator = new OpacityAnimator(targetElement);
     }
     if (animator == null)
     {
         throw new InvalidOperationException("The animation system could not be prepared for the target element.");
     }
 }