public CreateSaleCardViewModel()
 {
     ClickCommand = new Command(arg => ClickMethod());
     SaleCard = new SaleCardModel { Discount=15, Surname="", Name="", Number=0, Balance=0};
     SaleCards = XMLParser.GetAllSaleCards();
     xmlp = new XMLParser();
 }
 public ShowBalanceViewModel()
 {
     ClickCommand = new Command(arg => findBalance());
     SaleCard = new SaleCardModel { Discount=15, Name="", Surname="",Number=0, Balance=0 };
     SaleCards = XMLParser.GetAllSaleCards();
    
     xmlp = new XMLParser();
 }