public Parser blankPhrase() {
        if (blankPhraseParser == null) {
           FutureParser future = scoped("blankPhrase");
           blankPhraseParser = future;
           future.setParser(
               sequence(
                   token("BLANK"),
                   choice(
                       token("SCREEN"),
                       token("LINE")
                   )
               )
           );
        }

        return blankPhraseParser;
    }