code: def get_context_data(self, **kwargs):
          
          context = super(Sitemap, self).get_context_data(**kwargs)
          context.update(
              {'entries': Entry.published.all(),
               'categories': Category.published.all(),
               'authors': Author.published.all()}
          )
          return context
docs: Populate the context of the template
          with all published entries and all the categories.