public function update(GiftCard &$giftCard)
    {
        $data = $giftCard->exportData();
        $endpoint = '/admin/gift_cards/'.$giftCard->id.'.json';
        $response = $this->request(
            $endpoint, 'POST', array(
            'gift_card' => $data
            )
        );
        $giftCard->setData($response['gift_card']);
    }