code: func getUniqueID(timeUnix int64) (string, error) {
  	buf := bytes.NewBuffer(nil)
  	enc := base64.NewEncoder(base64.StdEncoding, buf)
  	if err := binary.Write(enc, binary.LittleEndian, timeUnix); err != nil {
  		enc.Close()
  		return "", err
  	}
  	if err := binary.Write(enc, binary.LittleEndian, rand.Uint64()); err != nil {
  		enc.Close()
  		return "", err
  	}
  	// encoder needs to be closed before buf.String(), defer does not work
  	// here
  	enc.Close()
  	return buf.String(), nil
  }
docs: // getUniqueID returns a base64 encoded unique ID that can be used for chunk/ack
  // mechanism, see
  // https://github.com/fluent/fluentd/wiki/Forward-Protocol-Specification-v1#option