code: func (q *TransmitLimitedQueue) getTransmitRange() (minTransmit, maxTransmit int) {
  	if q.lenLocked() == 0 {
  		return 0, 0
  	}
  	minItem, maxItem := q.tq.Min(), q.tq.Max()
  	if minItem == nil || maxItem == nil {
  		return 0, 0
  	}
  
  	min := minItem.(*limitedBroadcast).transmits
  	max := maxItem.(*limitedBroadcast).transmits
  
  	return min, max
  }
docs: // getTransmitRange returns a pair of min/max values for transmit values
  // represented by the current queue contents. Both values represent actual
  // transmit values on the interval [0, len). You must already hold the mutex.