code: func GetRandomDevAddr(p *redis.Pool, netID lorawan.NetID) (lorawan.DevAddr, error) {
  	var d lorawan.DevAddr
  	b := make([]byte, len(d))
  	if _, err := rand.Read(b); err != nil {
  		return d, errors.Wrap(err, "read random bytes error")
  	}
  	copy(d[:], b)
  	d.SetAddrPrefix(netID)
  
  	return d, nil
  }
docs: // GetRandomDevAddr returns a random DevAddr, prefixed with NwkID based on the
  // given NetID.