anchor.diff:    static final Map<String, Logger> _loggers = {};
   
     static _createRootLogger() =>
  -    new Logger._internal("", null)..logLevel = Level.WARNING;
  +    new Logger._internal("", "", null)..logLevel = Level.WARNING;
   
     /** Root logger. */
     static Logger get ROOT => new Logger('');
  
positive.code: 
  class Logger {
  
    final source;
    Level logLevel = null;
    Logger _parent;
  
negative.code:       parent = new Logger(source.substring(0, dot));
        thisName = source.substring(dot + 1);
      }
      return new Logger._internal(source, thisName, parent);
    }
  
    Logger._internal(this.fullSource, this.source, this._parent);
  
  }
  