public function listSubscriptions(
        $topicPath,
        ListSubscriptionsOptions $listSubscriptionsOptions = null
    ) {
        $listSubscriptionsPath = sprintf(
            Resources::LIST_SUBSCRIPTIONS_PATH,
            $topicPath
        );
        $response = $this->_listOptions(
            $listSubscriptionsOptions,
            $listSubscriptionsPath
        );
        $listSubscriptionsResult = new ListSubscriptionsResult();
        $listSubscriptionsResult->parseXml($response->getBody());

        return $listSubscriptionsResult;
    }