code: func handleStopNotifySpent(wsc *wsClient, icmd interface{}) (interface{}, error) {
  	cmd, ok := icmd.(*btcjson.StopNotifySpentCmd)
  	if !ok {
  		return nil, btcjson.ErrRPCInternal
  	}
  
  	outpoints, err := deserializeOutpoints(cmd.OutPoints)
  	if err != nil {
  		return nil, err
  	}
  
  	for _, outpoint := range outpoints {
  		wsc.server.ntfnMgr.UnregisterSpentRequest(wsc, outpoint)
  	}
  
  	return nil, nil
  }
docs: // handleStopNotifySpent implements the stopnotifyspent command extension for
  // websocket connections.