anchor.diff:  
     static const identicalFilesError =
         'Failed to load diff: OLD and NEW files are identical.';
  -
  -  static const artificialRootNodeName = 'ArtificialRoot';
  -
  -  static const mainNodeName = 'Main';
   
     CallGraph? _analysisCallGraph;
   
  
positive.code:   }
  
    bool _hasDeferredInfo(Map<String, dynamic> jsonFile) {
      return jsonFile['n'] == artificialRootNodeName;
    }
  
    Map<String, dynamic> _extractMainUnit(Map<String, dynamic> jsonFile) {
      if (_hasDeferredInfo(jsonFile)) {
        final main = _extractChildren(jsonFile).firstWhere(
          (child) => child['n'] == mainNodeName,
          orElse: () => jsonFile,
        );
        return main;
  
negative.code:   }
  
    Map<String, dynamic> _wrapInArtificialRoot(Map<String, dynamic> json) {
      json['n'] = _mainNodeName;
      return <String, dynamic>{
        'n': _artificialRootNodeName,
        'children': [json],
      };
    }
  