/**
  * Return an RSS feed of recent posts by tag.
  *
  * @param PostRepositoryInterface     $posts
  * @param ResponseFactory             $response
  * @param                             $category
  * @return \Illuminate\Http\Response|ResponseFactory
  */
 public function tag(PostRepositoryInterface $posts, ResponseFactory $response, $tag)
 {
     $response = $response->view('module::posts/rss', ['posts' => $posts->findManyByTag($tag)])->setTtl(3600);
     $response->headers->set('content-type', 'text/xml');
     return $response;
 }