def handle_exception(self, typ, error, tb):
        if isinstance(error, _RequestTimeout):
            if self._stream_ended:
                self.finish()
                return True
            else:
                error = HTTPError(599, "Timeout")

        self._remove_timeout()
        self._unregister_unfinished_streams()
        if hasattr(self, "stream_id"):
            self.context.remove_stream_delegate(self.stream_id)

            # FIXME: our nginx server will simply reset stream,
            # without increase the window size which consumed by
            # queued data frame which was belongs to the stream we're resetting
            # self.context.reset_stream(self.stream_id, flush=True)
            self.context.reset_stream_ids.append(self.stream_id)

        error.__traceback__ = tb
        response = HTTP2Response(self.request, 599, error=error, request_time=self.io_loop.time() - self.start_time)
        self._run_callback(response)
        return True

 def __init__(self, errno, message):
     HTTPError.__init__(self, 599, message)
     self.errno = errno

 def __init__(self, errno: int, message: str) -> None:
     HTTPError.__init__(self, 599, message)
     self.errno = errno

 def __init__(self, status_code, user_message, log_message=None, *args):
     HTTPError.__init__(self, status_code, log_message, *args) 
     self.user_message = user_message