private function canDelete(Article $article, User $user, $token)
 {
     if ($this->decisionManager->decide($token, array('ROLE_ADMIN'))) {
         return true;
     }
     if ($this->decisionManager->decide($token, array('ROLE_MODERATOR'))) {
         return $article->isAuthor($user);
     }
     return false;
 }