code: def add_extra_urls(self, item_session: ItemSession):
          '''Add additional URLs such as robots.txt, favicon.ico.'''
  
          if item_session.url_record.level == 0 and self._sitemaps:
              extra_url_infos = (
                  self.parse_url(
                      '{0}://{1}/robots.txt'.format(
                          item_session.url_record.url_info.scheme,
                          item_session.url_record.url_info.hostname_with_port)
                  ),
                  self.parse_url(
                      '{0}://{1}/sitemap.xml'.format(
                          item_session.url_record.url_info.scheme,
                          item_session.url_record.url_info.hostname_with_port)
                  )
              )
  
              for url_info in extra_url_infos:
                  item_session.add_child_url(url_info.urlf add_extra_urls(self, item_session: ItemSession):
          '''Add additional URLs such as robots.txt, favicon.ico.'''
  
          if item_session.url_record.level == 0 and self._sitemaps:
              extra_url_infos = (
                  self.parse_url(
                      '{0}://{1}/robots.txt'.format(
                          item_session.url_record.url_info.scheme,
                          item_session.url_record.url_info.hostname_with_port)
                  ),
                  self.parse_url(
                      '{0}://{1}/sitemap.xml'.format(
                          item_session.url_record.url_info.scheme,
                          item_session.url_record.url_info.hostname_with_port)
                  )
              )
  
              for url_info in extra_url_infos:
                  item_session.add_child_url(url_info.url)
docs: Add additional URLs such as robots.txt, favicon.ico.