code: def serve_forever(self, poll_interval=0.5):
          
          self.__is_shut_down.clear()
          try:
              while not self.__shutdown_request:
                  r, w, e = _eintr_retry(select.select, [self], [], [], poll_interval)
                  if self in r:
                      self._handle_request_noblock()
  
          finally:
              self.__shutdown_request = False
              self.__is_shut_down.set()
docs: Handle one request at a time until shutdown.
          Polls for shutdown every poll_interval seconds. Ignores
          self.timeout. If you need to do periodic tasks, do them in
          another thread.