anchor.diff:        'Could not read the "pubspec.yaml` file associated with this package. '
         'Usage of package:$_annotationPkgName could not be verified.',
       );
  -    return null;
  +    return;
     }
   
     Future<Pubspec> readPubspec(AssetId asset) async {
  
positive.code: 
    final pubspec = await readPubspec(pubspecAssetId);
  
    return _checkAnnotationConstraint(
      pubspec,
      !production,
    );
  }
  
  String? _checkAnnotationConstraint(
  
negative.code:   return null;
  }
  
  class _OncePerBuild {
    final bool state;
    final FutureOr<void> Function(bool, BuildStep) _callback;
    bool _ran = false;
  
    _OncePerBuild(this.state, this._callback);
  
    Future<void> run(BuildStep buildStep) async {
      if (!_ran) {
        _ran = true;
        await _callback(state, buildStep);
      }
    }
  }
  
  