public function thumbnail(Group $group, File $file)
 {
     if (in_array($file->mime, ['image/jpeg', 'image/png', 'image/gif'])) {
         $cachedImage = Image::cache(function ($img) use($file) {
             return $img->make(storage_path() . '/app/' . $file->path)->fit(32, 32);
         }, 60000, true);
         return $cachedImage->response();
     }
     if ($file->isFolder()) {
         return redirect('images/extensions/folder.png');
     }
     return redirect('images/extensions/text-file.png');
 }