anchor.diff:        var NAME = current;
         if (next(TokenType.COLON)) {
           var COLON = current;
  -        var val = parseValueOrVariable();
  +        var val = parseInputValue();
           if (val != null)
             return new ArgumentContext(NAME, COLON, val);
           else {
  
positive.code: 
          if (next(TokenType.COLON)) {
            var COLON = current;
            var val = parseValueOrVariable();
            if (val != null)
              return new DirectiveContext(
                  ARROBA, NAME, COLON, null, null, null, val);
  
negative.code:   DefaultValueContext parseDefaultValue() {
      if (next(TokenType.EQUALS)) {
        var EQUALS = current;
        var value = parseInputValue();
        if (value != null) {
          return new DefaultValueContext(EQUALS, value);
        } else {
  