public static function getItems($array, $keys = null)
    {
        if (is_null($keys)) {
            return $array;
        } elseif (is_scalar($keys)) {
            $keys = [$keys => $array[$keys]];
        }
        $res = [];
        foreach ($keys as $k) {
            if (array_key_exists($k, $array)) {
                $res[$k] = $array[$k];
            }
        }
        return $res;
    }