code: func ParseMACAddress(s string) (LinkAddress, error) {
  	parts := strings.FieldsFunc(s, func(c rune) bool {
  		return c == ':' || c == '-'
  	})
  	if len(parts) != 6 {
  		return "", fmt.Errorf("inconsistent parts: %s", s)
  	}
  	addr := make([]byte, 0, len(parts))
  	for _, part := range parts {
  		u, err := strconv.ParseUint(part, 16, 8)
  		if err != nil {
  			return "", fmt.Errorf("invalid hex digits: %s", s)
  		}
  		addr = append(addr, byte(u))
  	}
  	return LinkAddress(addr), nil
  }
docs: // ParseMACAddress parses an IEEE 802 address.
  //
  // It must be in the format aa:bb:cc:dd:ee:ff or aa-bb-cc-dd-ee-ff.