public Parser exitStatement() {
        if (exitStatementParser == null) {
           FutureParser future = scoped("exitStatement");
           exitStatementParser = future;
           future.setParser(
               sequence(
                   token("EXIT"),
                   optional(
                       choice(
                           sequence(
                               token("PROGRAM"),
                               optional(
                                   returningPhrase()
                               )
                           ),
                           token("PARAGRAPH"),
                           token("SECTION"),
                           sequence(
                               token("PERFORM"),
                               optional(
                                   token("CYCLE")
                               )
                           ),
                           token("METHOD"),
                           token("FUNCTION"),
                           token("ITERATOR")
                       )
                   )
               )
           );
        }

        return exitStatementParser;
    }