anchor.diff:        throw new UnsupportedError("StringSource doesn't support uriKind.");
   
     @override
  -  Uri get uri => new Uri.file(fullName);
  +  Uri get uri => new Uri(path: fullName);
   
     @override
     int get hashCode => _contents.hashCode ^ fullName.hashCode;
  
positive.code:       return null;
      }
  
      return context.getSource(uri.path);
    }
  }
  
  
negative.code: String dirname(String path) {
    int index = path.lastIndexOf('/');
    return index == -1 ? '' : path.substring(0, index);
  }
  
  String pathconcat(String path1, String path2) {
    if (path1.isEmpty) {
      return path2;
    }
    if (path2.isEmpty){
      return path1;
    }
    if (path1.endsWith("/") || path2.startsWith("/")) {
      return path1 + path2;
    }
    return path1 + "/" + path2;
  }
  
  /**
  