public static function cloneRelations($sources, $clones, $relations = [])
    {
        if (!is_array($sources)) {
            $sources = [$sources];
            $clones = [$clones];
        }
        foreach ($sources as $k => $source) {
            foreach ($relations as $j => $name) {
                list($name, $except) = is_array($name) ? [$j, $name] : [$name, ['id']];
                (new static($source, $name))->cloneRelation($clones[$k], $except);
            }
        }
    }