protected override void RegisterCommands()
        {
            base.RegisterCommands();
            AddDigitCommand = new KioskParameterisedCommand<string>(ExecuteAddDigitCommand, CanExecuteAddDigitCommand, true);
            AddDigitCommand.ExecutionCompleted += Command_ExecutionCompleted;

            BackspaceCommand = new KioskCommand(ExecuteBackspaceCommand, CanExecuteBackspaceCommand, true);
            BackspaceCommand.ExecutionCompleted += Command_ExecutionCompleted;
        }
 protected override void RegisterCommands()
 {
     SubmitCommand = new KioskParameterisedCommand<string>(ExecuteSubmitCommand, CanExecuteSubmitCommand);
     CancelCommand = new KioskCommand(ExecuteCancelCommand, CanExecuteCancelCommand);
 }