public function create($account, $name, $description = null, $url = null)
    {
        $params = array('name' => $name);

        if (!is_null($description)) {
            $params['description'] = $description;
        }

        if (!is_null($url)) {
            $params['url'] = $url;
        }

        return $this->requestPost(
            sprintf('users/%s/consumers', $account),
            $params
        );
    }