* @return {@link Inet4Address} of embedded IPv4 in an ISATAP address
   * @throws IllegalArgumentException if the argument is not a valid IPv6 ISATAP address
   */
  public static Inet4Address getIsatapIPv4Address(Inet6Address ip) {
    checkArgument(isIsatapAddress(ip), "Address '%s' is not an ISATAP address.", toAddrString(ip));

    return getInet4Address(Arrays.copyOfRange(ip.getAddress(), 12, 16));
  }

  /**

   * @return {@link Inet4Address} of embedded IPv4 in an ISATAP address
   * @throws IllegalArgumentException if the argument is not a valid IPv6 ISATAP address
   */
  public static Inet4Address getIsatapIPv4Address(Inet6Address ip) {
    checkArgument(isIsatapAddress(ip), "Address '%s' is not an ISATAP address.", toAddrString(ip));

    return getInet4Address(Arrays.copyOfRange(ip.getAddress(), 12, 16));
  }

  /**