anchor.diff:    AssetBundleProxy _bundle;
     Map<String, ImageResource> _imageCache = new Map<String, ImageResource>();
     Map<String, Future<String>> _stringCache = new Map<String, Future<String>>();
  -
  -  void close() {
  -    _bundle.close();
  -    _bundle = null;
  -    _imageCache = null;
  -  }
   
     Future<ui.Image> _fetchImage(String key) async {
       return await decodeImageFromDataPipe(await load(key));
  
positive.code:   NetworkAssetBundle(Uri baseUrl) : _baseUrl = baseUrl;
  
    final Uri _baseUrl;
  
    void close() { }
  
    String _urlFromKey(String key) => _baseUrl.resolve(key).toString();
  
  
negative.code: import 'shell.dart';
  
  abstract class AssetBundle {
    ImageResource loadImage(String key);
    Future<String> loadString(String key);
    Future<core.MojoDataPipeConsumer> load(String key);
  