code: func (b *VrfLabelBody) Serialize(version uint8) ([]byte, error) {
  	buf := make([]byte, 6)
  	binary.BigEndian.PutUint32(buf[0:4], b.Label)
  	buf[4] = uint8(b.Afi)
  	buf[5] = uint8(b.LabelType)
  	return buf, nil
  }
docs: // Reference: zclient_send_vrf_label in lib/zclient.c of FRR 5.x and 6.x