public Parser interfaceSpecifier() {
        if (interfaceSpecifierParser == null) {
           FutureParser future = scoped("interfaceSpecifier");
           interfaceSpecifierParser = future;
           future.setParser(
               sequence(
                   token("INTERFACE"),
                   interfaceName(),
                   optional(
                       sequence(
                           token("AS"),
                           literal()
                       )
                   ),
                   optional(
                       sequence(
                           token("EXPANDS"),
                           interfaceName(),
                           token("USING"),
                           choice(
                               className(),
                               interfaceName()
                           )
                       )
                   )
               )
           );
        }

        return interfaceSpecifierParser;
    }