code: def _client_request_callback(self, request: Request):
          '''Request callback handler.'''
          self._item_session = self._new_item_session(request)
          self._item_session.request = request
  
          if self._cookie_jar:
              self._cookie_jar.add_cookie_header(request)
  
          verdict, reason = self._fetch_rule.check_subsequent_web_request(self._item_session)
          self._file_writer_session.process_request(request)
  
          if verdict:
              _logger.info(__(
                  _('Fetching ‘{url}’.'),
                  url=request.url_info.url
              ))
  
          return verdicf _client_request_callback(self, request: Request):
          '''Request callback handler.'''
          self._item_session = self._new_item_session(request)
          self._item_session.request = request
  
          if self._cookie_jar:
              self._cookie_jar.add_cookie_header(request)
  
          verdict, reason = self._fetch_rule.check_subsequent_web_request(self._item_session)
          self._file_writer_session.process_request(request)
  
          if verdict:
              _logger.info(__(
                  _('Fetching ‘{url}’.'),
                  url=request.url_info.url
              ))
  
          return verdict
docs: Request callback handler.