public function get($keys, $default = null)
    {
        $result = $this->data;
        foreach (is_array($keys) ? $keys : [$keys] as $key) {
            if (is_array($result) && isset($result[$key])) {
                $result = $result[$key];
            } else {
                $result = $default;
                break;
            }
        }
        return $result;
    }