public static function createFromJSON($json_obj)
    {
        $result = new self();
        foreach ($json_obj as $k => $v) {
            if ($k == "months") {
                $result->$k = $v->month;
            }
            else if ($k == "weekDays") {
                $result->$k = $v->day;
            }
            else {
                $result->$k = $v;
            }
        }
        return $result;
    }