code: def common_log(environ, response, response_time=None):
      
  
      logger = logging.getLogger()
  
      if response_time:
          formatter = ApacheFormatter(with_response_time=True)
          try:
              log_entry = formatter(response.status_code, environ,
                                    len(response.content), rt_us=response_time)
          except TypeError:
              # Upstream introduced a very annoying breaking change on the rt_ms/rt_us kwarg.
              log_entry = formatter(response.status_code, environ,
                                    len(response.content), rt_ms=response_time)
      else:
          formatter = ApacheFormatter(with_response_time=False)
          log_entry = formatter(response.status_code, environ,
                                len(response.content))
  
      logger.info(log_entry)
  
      return log_entry
docs: Given the WSGI environ and the response,
      log this event in Common Log Format.