public static List <MovieHall> GetMovieHallsByCinemaId(int cinemaId)
        {
            var cinema = Cinemas.SingleOrDefault(x => x.ID == cinemaId);

            if (cinema == null)
            {
                return(new List <MovieHall>());
            }
            return(cinema.MovieHalls);
        }
 public static Cinema GetCinemaByCinemaId(int id)
 {
     return(Cinemas.SingleOrDefault(x => x.ID == id));
 }