public function retrieve($id, $params = null, $opts = null)
{
list($url, $params) = $this->extractPathAndUpdateParams($params);
$id = Util\Util::utf8($id);
$extn = urlencode($id);
list($response, $opts) = $this->_request('get', "{$url}/{$extn}", $params, $opts);
$this->_requestParams = $params;
return Util\Util::convertToStripeObject($response, $opts);
}