/// <summary>
 /// This method checks if the card is matched. If it is not matched image is hidden.
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void PeekTimer_Tick(object sender, EventArgs e)
 {
     foreach (var slide in CardCollection)
     {
         if (!slide.IsMatched)
         {
             slide.CloseCard();
             CanSelect = true;
         }
     }
     OnPropertyChanged("AreSlidesActive");
     TimerForChoosing.Stop();
 }
 /// <summary>
 /// This method hiddes all card that are not matched.
 /// </summary>
 public void HideUnmatched()
 {
     TimerForChoosing.Start();
 }