public Parser dataOutput() {
        if (dataOutputParser == null) {
           FutureParser future = scoped("dataOutput");
           dataOutputParser = future;
           future.setParser(
               sequence(
                   optional(
                       token("BY")
                   ),
                   token("OUTPUT"),
                   star(
                       sequence(
                           dataName(),
                           token("AS"),
                           typeName(),
                           optional(
                               attributeClause()
                           )
                       )
                   )
               )
           );
        }

        return dataOutputParser;
    }