public Parser concatenatedLiteral() {
        if (concatenatedLiteralParser == null) {
           FutureParser future = scoped("concatenatedLiteral");
           concatenatedLiteralParser = future;
           future.setParser(
               sequence(
                   token("&"),
                   choice(
                       literalValue(),
                       constant()
                   )
               )
           );
        }

        return concatenatedLiteralParser;
    }