public static void AddProduct(Product product, List <int> patlangacIds)
        {
            product.Id = products.Last().Id + 1;

            product.Category = categories.First(t => t.Id == product.CategoryId);

            product.Patlangacs = new List <Patlangac>();

            foreach (int patlangacId in patlangacIds)
            {
                Patlangac patlangac = patlangacs.First(t => t.Id == patlangacId);
                product.Patlangacs.Add(patlangac);
            }



            products.Add(product);
        }
        public static void UpdateProduct(Product product, List <int> patlangacIds)
        {
            for (int i = 0; i < products.Count; i++)
            {
                if (products[i].Id == product.Id)
                {
                    products[i] = product;
                    break;
                }
            }

            product.Category   = categories.First(y => y.Id == product.CategoryId);
            product.Patlangacs = new List <Patlangac>();


            foreach (int patlangacId in patlangacIds)
            {
                Patlangac patlangac = patlangacs.First(t => t.Id == patlangacId);
                product.Patlangacs.Add(patlangac);
            }
        }