public int AddProductReview(int prodId, Review review)
 {
     review.ProdId = prodId;
     review.Id = nextReviewId++;
     reviews.Add(review);
     return review.Id;
 }
 public int UpdateProductReview(Review review)
 {
     var prodReview = GetProductReview(review.ProdId, review.Id);
     if (prodReview == null)
         return AddProductReview(review.ProdId, review);
     else
     {
         reviews.Remove(prodReview);
         reviews.Add(review);
         return review.Id;
     }
 }