anchor.diff:     * we find a String and nextTokenIsImportant is false we can stop the scan.
      */
     bool _nextTokenIsImportant;
  +  String _keywordBefore;
     
     /**
      * Create new instance of [Scanner] to parse a instance of [Runes]. The 
  
positive.code:       _log("'$keyword' is a keyword!");
        
        _nextTokenIsImportant = true;
        return next;
      } else {
        /* This is not a keyword but an identifier. Because identifiers is not
  
negative.code:        * finish.
         */
        _log("'$keyword' is an identifier!");
        _log("     and _nextTokenIsImportant = $_nextTokenIsImportant");
        _log("     and _keywordBefore = $_keywordBefore");
        
        if (_nextTokenIsImportant) {
          return (_keywordBefore == "part" && keyword == "of") ? _U.$EOF : next;
        } else {
          return _U.$EOF;
        }
      }
      // END: Keyword check
  