-def book_fragments(request, book, theme_slug):
-    kwargs = models.Book.split_urlid(book)
-    if kwargs is None:
-        raise Http404
-    book = get_object_or_404(models.Book, **kwargs)
+def book_fragments(request, slug, theme_slug):
+    book = get_object_or_404(models.Book, slug=slug)