public function common($users)
    {
        if ($users instanceof \Illuminate\Database\Eloquent\Collection) {
            $users = $users->map(function ($user) {
                return $user->getKey();
            });
        }

        return $this->withCount(['users' => function ($query) use ($users) {
            $query->whereIn(Chat::userModelPrimaryKey(), $users);
        }])->get()->filter(function ($conversation, $key) use ($users) {
            return $conversation->users_count == count($users);
        });
    }