anchor.diff:    bool _processNext() {
       while (_bufferList.length > 0) {
         int byte = _bufferList.next();
  -      _result.addCharCode(byte);
  +      _result.add(byte);
       }
       return true;
     }
  
positive.code:       if (byte > 127) {
          throw new DecoderException("Illegal ASCII character $byte");
        }
        _result.addCharCode(byte);
      }
      return true;
    }
  
negative.code:   abstract bool _processNext();
  
    _BufferList _bufferList;
    List<int> _result;
  }
  
  
  