code: def get_sites(self, entry):
          
          try:
              index_url = reverse('zinnia:entry_archive_index')
          except NoReverseMatch:
              index_url = ''
          return format_html_join(
              ', ', '<a href="{}://{}{}" target="blank">{}</a>',
              [(settings.PROTOCOL, site.domain, index_url,
                conditional_escape(site.name)) for site in entry.sites.all()])
docs: Return the sites linked in HTML.