/// <summary>
 ///
 /// </summary>
 /// <param name="windowManager"></param>
 /// <param name="counter"></param>
 public OperationViewModel(IWindowManager windowManager, Counter counter)
 {
     this.windowManager = windowManager;
     Counter = counter;
 }
 /// <summary>
 ///
 /// </summary>
 /// <param name="windowManager"></param>
 /// <param name="counter"></param>
 public ResultViewModel(IWindowManager windowManager, Counter counter)
 {
     this.windowManager = windowManager;
     Counter = counter;
 }