text: from django.contrib.sitemaps import Sitemap
  from cvk_2015.models import CVK2015Model
  
  
  class CVK2015Sitemap(Sitemap):
      changefreq = "monthly"
      protocol = "https"
      limit = 50000
  
      def items(self):
          return CVK2015Model.objects.only("id", "last_updated_from_dataset").order_by("pk")
  