public VictorinaSpecificPage(Models.Victorina _victorina)
        {
            InitializeComponent();

            OurVictorina        = _victorina;
            this.BindingContext = OurVictorina;
        }
 public async void OnVictorinaItemTapped(object sender, ItemTappedEventArgs e)
 {
     Models.Victorina selectedVictorina = e.Item as Models.Victorina;
     if (selectedVictorina != null)
     {
         await Navigation.PushAsync(new VictorinaSpecificPage(selectedVictorina));
     }
     ((ListView)sender).SelectedItem = null;
 }