public CountryDetailsViewModel()
        {
            XmlCountryService countryRepository = new XmlCountryService();
            CountryData country = countryRepository.GetCountryById(Navigation.Id);

            DataContext = country;
        }
 public MainPageViewModel()
 {
     XmlCountryService countryRepository = new XmlCountryService();
     ListItemsSource = countryRepository.GetCountryList();
 }