public function start_batch() {
        return new BatchAPI(
            $this->API_KEY,
            array(
                'API_HOST' => $this->API_HOST,
                'API_PROTO' => $this->API_PROTO,
                'API_PORT' => $this->API_PORT,
                'API_VERSION' => $this->API_VERSION,
                'DEBUG' => $this->DEBUG,
            )
        );
    }