public Parser addStatement() {
        if (addStatementParser == null) {
           FutureParser future = scoped("addStatement");
           addStatementParser = future;
           future.setParser(
               sequence(
                   token("ADD"),
                   choice(
                       addition_format1(),
                       addition_format2(),
                       addition_format3()
                   ),
                   optional(
                       sequence(
                           optional(
                               token("ON")
                           ),
                           token("SIZE"),
                           token("ERROR"),
                           nestedStatements()
                       )
                   ),
                   optional(
                       sequence(
                           token("NOT"),
                           optional(
                               token("ON")
                           ),
                           token("SIZE"),
                           token("ERROR"),
                           nestedStatements()
                       )
                   ),
                   optional(
                       token("END-ADD")
                   )
               )
           );
        }

        return addStatementParser;
    }