$chapters = Chapter::visible()->where('book_id', '=', $this->book->id)->get();
$all = collect()->concat($pages)->concat($chapters);
$chapterMap = $chapters->keyBy('id');
$chapters = Chapter::visible()->where('book_id', '=', $this->book->id)->get();
$all = collect()->concat($pages)->concat($chapters);
$chapterMap = $chapters->keyBy('id');