public Parser callUsing() {
        if (callUsingParser == null) {
           FutureParser future = scoped("callUsing");
           callUsingParser = future;
           future.setParser(
               sequence(
                   token("USING"),
                   plus(
                       choice(
                           sequence(
                               optional(
                                   sequence(
                                       optional(
                                           token("BY")
                                       ),
                                       token("REFERENCE")
                                   )
                               ),
                               choice(
                                   sequence(
                                       token("ADDRESS"),
                                       token("OF"),
                                       identifier()
                                   ),
                                   token("OMITTED"),
                                   identifier(),
                                   literal()
                               )
                           ),
                           sequence(
                               optional(
                                   token("BY")
                               ),
                               token("CONTENT"),
                               choice(
                                   sequence(
                                       token("LENGTH"),
                                       token("OF"),
                                       identifier()
                                   ),
                                   arithmeticExpression(),
                                   identifier(),
                                   literal()
                               )
                           ),
                           sequence(
                               optional(
                                   token("BY")
                               ),
                               token("VALUE"),
                               choice(
                                   sequence(
                                       token("LENGTH"),
                                       token("OF"),
                                       identifier(),
                                       optional(
                                           sequence(
                                               token("SIZE"),
                                               optional(
                                                   token("IS")
                                               ),
                                               optional(
                                                   choice(
                                                       sequence(
                                                           token("LENGTH"),
                                                           token("OF"),
                                                           identifier()
                                                       ),
                                                       integer()
                                                   )
                                               )
                                           )
                                       )
                                   ),
                                   sequence(
                                       integer(),
                                       token("SIZE"),
                                       optional(
                                           token("IS")
                                       ),
                                       optional(
                                           choice(
                                               sequence(
                                                   token("LENGTH"),
                                                   token("OF"),
                                                   identifier()
                                               ),
                                               integer()
                                           )
                                       )
                                   ),
                                   arithmeticExpression(),
                                   identifier(),
                                   literal()
                               )
                           )
                       )
                   )
               )
           );
        }

        return callUsingParser;
    }