private async void OnBuyTicket()
        {
            var response = await Application.Current.MainPage
                           .DisplayAlert("Buy", "Are you sure?",
                                         "Yes", "No");

            if (response && Function.Value.HasValue)
            {
                using (UserDialogs.Instance.Loading())
                {
                    await _moviesService.BuyTicketFor(CurrentMovie.Value.Id, Function.Value.Value);
                }
                await _navigationService.GoToTicketPage();
            }
        }