Chargify::getCustomerSubscriptionByCId PHP Method

    public function getCustomerSubscriptionByCId($client_id)
    {
        $r = $this->sendRequest("/customers/{$client_id}/subscriptions.xml", 'GET');
        if ($r->getResponseCode() == 200) {
            $xml_node = new SimpleXMLElement($r->getBody()->toString());
            $subscription = new ChargifySubscription($xml_node);
            return $subscription;
        } else {
            if ($r->getResponseCode() == 422) {
                $xml_node = new SimpleXMLElement($r->getBody()->toString());
                if ($xml_node->error) {
                    return (string) $xml_node->error;
                }
            }
            throw new Exception("Cannot get subscription info. Response code: " . $r->getResponseCode() . ". Response body: " . $r->getBody()->toString());
        }
    }