import 'package:mobile/models/product.dart'; abstract class Server { Future<Response<List<Product>>> allProducts(); Future<Response<Null>> register( String name, String email, String password, ); Future<Response<Null>> login( String name, String email, String password, ); } sealed class Response<Data> {} class Success<Data> extends Response<Data> { Data data; Success({required this.data}); } class Error<Data> extends Response<Data> { String message; Error({required this.message}); }