code: def _extract_field_with_regex(self, field):
          
          matched = re.search(field, self.text)
          if not matched:
              err_msg = u"Failed to extract data with regex! => {}\n".format(field)
              err_msg += u"response body: {}\n".format(self.text)
              logger.log_error(err_msg)
              raise exceptions.ExtractFailure(err_msg)
  
          return matched.group(1)
docs: extract field from response content with regex.
              requests.Response body could be json or html text.
  
          Args:
              field (str): regex string that matched r".*\(.*\).*"
  
          Returns:
              str: matched content.
  
          Raises:
              exceptions.ExtractFailure: If no content matched with regex.
  
          Examples:
              >>> # self.text: "LB123abcRB789"
              >>> filed = "LB[\d]*(.*)RB[\d]*"
              >>> _extract_field_with_regex(field)
              abc