code: func (nc *Conn) QueueSubscribeSync(subj, queue string) (*Subscription, error) {
  	mch := make(chan *Msg, nc.Opts.SubChanLen)
  	s, e := nc.subscribe(subj, queue, nil, mch, true)
  	return s, e
  }
docs: // QueueSubscribeSync creates a synchronous queue subscriber on the given
  // subject. All subscribers with the same queue name will form the queue
  // group and only one member of the group will be selected to receive any
  // given message synchronously using Subscription.NextMsg().