We need to implement functionality to prevent users from adding the same product to their wishlist multiple times. To achieve this, before adding a product to the wishlist, we should check if the product is already present in the user's wishlist. If the product is already on the wishlist, we should provide a notification to the user, indicating that the product is already added. Otherwise, if the product is not on the wishlist, we can proceed to add it. This ensures a seamless and user-friendly experience, preventing duplicate entries in the wishlist