private function whenCommented(Commented $event)
 {
     $comment = new ReadModel\Comment();
     $comment->id = $event->commentId();
     $comment->body = $event->body();
     $comment->author = $event->author();
     $this->articles[(string) $event->articleId()]->comments[(string) $event->commentId()] = $comment;
 }
 private function whenCommented(Commented $event)
 {
     $this->articles[(string) $event->articleId()]['commentCount']++;
 }
 private function whenCommented($data, Commented $event)
 {
     $data[(string) $event->articleId()]['commentCount']++;
     return $data;
 }