public async void SaveAsync()
{
await MovieCatalog.SaveAsync();
await TheaterCatalog.SaveAsync();
await ShowCatalog.SaveAsync();
await TicketCatalog.SaveAsync();
}
public async void LoadAsync()
{
await MovieCatalog.LoadAsync();
await TheaterCatalog.LoadAsync();
await ShowCatalog.LoadAsync();
await TicketCatalog.LoadAsync();
}