public function getPrivilege(string $id = null): array
    {
        if ($id) {
            if (is_numeric($id)) {
                $filter = array_filter($this->privilege, function ($row) use ($id) { return $row['id'] == $id; });
                return (array) array_pop($filter);
            }
            return (array) ($this->privilege[$id] ?? []);
        }
        return $this->privilege;
    }