public function create($priceRuleId, DiscountCode &$discountCode)
    {
        $data = $discountCode->exportData();
        $endpoint = '/admin/price_rules/'.$priceRuleId.'/discount_codes.json';
        $response = $this->request($endpoint, 'POST', array(
            'discount_code' => $data
        ));
        $discountCode->setData($response['discount_code']);
    }