doc(arch): add fully featured example

packages/wyatt_architecture/example/lib/domain/data_sources/local/favorite_local_data_source.dart

@@ -0,0 +1,25 @@
+// Copyright (C) 2022 WYATT GROUP
+// Please see the AUTHORS file for details.
+// 
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+// 
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+import 'package:architecture_example/domain/entities/photo.dart';
+import 'package:wyatt_architecture/wyatt_architecture.dart';
+
+abstract class FavoriteLocalDataSource extends BaseLocalDataSource {
+  Future<void> addPhotoToFavorites(Photo photo);
+  Future<void> deletePhotoFromFavorites(int id);
+  Future<List<int>> getAllPhotosFromFavorites();
+  Future<bool> checkIfPhotoIsInFavorites(int id);
+}