# golang
tai64n := make([]byte, 12)
binary.BigEndian.PutUint64(tai64n[:], 4611686018427387914+uint64(now.Unix()))
binary.BigEndian.PutUint32(tai64n[8:], uint32(now.Nanosecond()))

# python
now = datetime.datetime.now()
tai = struct.pack('!qi', 4611686018427387914 + int(now.timestamp()), int(now.microsecond * 1e3))