public Parser gobackStatement() {
        if (gobackStatementParser == null) {
           FutureParser future = scoped("gobackStatement");
           gobackStatementParser = future;
           future.setParser(
               sequence(
                   token("GOBACK"),
                   optional(
                       sequence(
                           choice(
                               token("GIVING"),
                               token("RETURNING")
                           ),
                           choice(
                               sequence(
                                   optional(
                                       sequence(
                                           token("ADDRESS"),
                                           token("OF")
                                       )
                                   ),
                                   identifier()
                               ),
                               integer()
                           )
                       )
                   )
               )
           );
        }

        return gobackStatementParser;
    }