code: func (d *Device) AdvertiseIBeacon(ctx context.Context, u ble.UUID, major, minor uint16, pwr int8) error {
  	b := make([]byte, 21)
  	copy(b, ble.Reverse(u))                   // Big endian
  	binary.BigEndian.PutUint16(b[16:], major) // Big endian
  	binary.BigEndian.PutUint16(b[18:], minor) // Big endian
  	b[20] = uint8(pwr)                        // Measured Tx Power
  	return d.AdvertiseIBeaconData(ctx, b)
  }
docs: // AdvertiseIBeacon advertises iBeacon packet.