public Parser notOnException() {
        if (notOnExceptionParser == null) {
           FutureParser future = scoped("notOnException");
           notOnExceptionParser = future;
           future.setParser(
               sequence(
                   token("NOT"),
                   optional(
                       token("ON")
                   ),
                   token("EXCEPTION"),
                   nestedStatements()
               )
           );
        }

        return notOnExceptionParser;
    }