code: def get_nodes(self, request):
          
          nodes = []
          nodes.append(NavigationNode(_('Categories'),
                                      reverse('zinnia:category_list'),
                                      'categories'))
          for category in Category.objects.all():
              nodes.append(NavigationNode(category.title,
                                          category.get_absolute_url(),
                                          category.pk, 'categories'))
          return nodes
docs: Return menu's node for categories