public Genre Update(Genre genre)
 {
     var gen = _context.Genres.FirstOrDefault(cp => cp.Id == genre.Id);
     if (gen == null) throw new ArgumentException();
     _context.Entry(genre).State = System.Data.Entity.EntityState.Modified;
     _context.SaveChanges();
     return gen;
 }
 public Genre Delete(Genre genre)
 {
     var gen = _context.Genres.Remove(genre);
     _context.SaveChanges();
     return gen;
 }
 public Genre Create(Genre genre)
 {
     var gen = _context.Genres.Add(genre);
     _context.SaveChanges();
     return gen;
 }