Creating a shopping cart application with Riverpod

Create a new Flutter app named cart_riverpod and copy item.dart into your lib folder, as we have been doing in the previous sections. Add dependencies for equatable and flutter_riverpod from pub.dev. Let's get started, as follows:

1. Create a new file named cart_model.dart and add the following code to it:

   import 'item.dart';
   import 'package:flutter_riverpod/flutter_riverpod.dart';
   final cartProvider = StateNotifierProvider((ref) => CartNotifier());
   class CartNotifier extends StateNotifier<CartModel> {
     CartNotifier() : super(CartModel(cart: []));
     void addToCart(Item item) {
       var updatedCart = state.cart;
       updatedCart.add(item);
       state = CartModel(cart: updatedCart);
     }
     void removeFromCart(Item item) {
       var updatedCart = state.cart;
       updatedCart...