public Parser whenSetToFalseClause() {
        if (whenSetToFalseClauseParser == null) {
           FutureParser future = scoped("whenSetToFalseClause");
           whenSetToFalseClauseParser = future;
           future.setParser(
               sequence(
                   optional(
                       token("WHEN")
                   ),
                   optional(
                       token("SET")
                   ),
                   optional(
                       token("TO")
                   ),
                   token("FALSE"),
                   optional(
                       token("IS")
                   ),
                   literal()
               )
           );
        }

        return whenSetToFalseClauseParser;
    }