public function city($city_id, Request $request = null)
    {
        $city = City::find($city_id);

        if ($request) {
            $included = [];
            $query = $city->getInlcudeResources($request->include);
            if ($query) {
                $collection = new Collection($query, $request->include);
                $included = $collection->toArray();
            }
            $links = $request ? ['self' => $request->url()] : [];
            return $this->respondWithItem($city, 'city', $links, $included);
        }
        return $city;
    }