code: def by_publications(self):
          
          if not spectator_apps.is_enabled('reading'):
              raise ImproperlyConfigured("To use the CreatorManager.by_publications() method, 'spectator.reading' must by in INSTALLED_APPS.")
  
          qs = self.get_queryset()
  
          qs = qs.exclude(publications__reading__isnull=True) \
                      .annotate(num_publications=Count('publications')) \
                      .order_by('-num_publications', 'name_sort')
  
          return qs
docs: The Creators who have been most-read, ordered by number of read
          publications (ignoring if any of those publicatinos have been read
          multiple times.)
  
          Each Creator will have a `num_publications` attribute.