code: def closed(self, code, reason=None):
          
          if code != 1000:
              self._error = errors.SignalFlowException(code, reason)
              _logger.info('Lost WebSocket connection with %s (%s: %s).',
                           self, code, reason)
              for c in self._channels.values():
                  c.offer(WebSocketComputationChannel.END_SENTINEL)
          self._channels.clear()
          with self._connection_cv:
              self._connected = False
              self._connection_cv.notify()
docs: Handler called when the WebSocket is closed. Status code 1000
          denotes a normal close; all others are errors.