public Parser valueIsOperator() {
        if (valueIsOperatorParser == null) {
           FutureParser future = scoped("valueIsOperator");
           valueIsOperatorParser = future;
           future.setParser(
               choice(
                   token("AND"),
                   token("OR"),
                   token("&"),
                   token("+"),
                   token("-"),
                   token("*"),
                   token("/")
               )
           );
        }

        return valueIsOperatorParser;
    }