public function schedules($options = array())
    {
        if ($this['object'] === 'customer') {
            if (is_array($options)) {
                $options = '?' . http_build_query($options);
            }

            return parent::g_retrieve('OmiseScheduleList', self::getUrl($this['id'] . '/schedules' . $options), $this->_publickey, $this->_secretkey);
        }
    }