}
    }

    /**
     * Returns a hash of empty values for all the values that are in the given
     * StripeObject.
     */
    public static function emptyValues($obj)
    {
        if (is_array($obj)) {
            $values = $obj;
        } elseif ($obj instanceof StripeObject) {
            $values = $obj->_values;
        } else {
            throw new \InvalidArgumentException(
                "empty_values got got unexpected object type: " . get_class($obj)
            );
        }
        $update = array_fill_keys(array_keys($values), "");
        return $update;
    }

    /**
     * @return object The last response from the Stripe API
     */
    public function getLastResponse()
    {
        return $this->_lastResponse;
    }

    /**
     * @param ApiResponse
     *
     * @return void Set the last response from the Stripe API
     */
    public function setLastResponse($resp)
    {
        $this->_lastResponse = $resp;
    }
}