* @return {@code true} if the argument is a 6to4 address
   */
  public static boolean is6to4Address(Inet6Address ip) {
    byte[] bytes = ip.getAddress();
    return (bytes[0] == (byte) 0x20) && (bytes[1] == (byte) 0x02);
  }

  /**
   * Returns the IPv4 address embedded in a 6to4 address.
   *
   * @param ip {@link Inet6Address} to be examined for embedded IPv4 in 6to4 address

	b := uint8(t.class) << 6
	if t.isCompound {
		b |= 0x20
	}
	if t.tag >= 31 {
		b |= 0x1f
		dst = append(dst, b)
		dst = appendBase128Int(dst, int64(t.tag))
	} else {
		b |= uint8(t.tag)
		dst = append(dst, b)
	}

	if t.length >= 128 {
		l := lengthLength(t.length)
		dst = append(dst, 0x80|byte(l))
		dst = appendLength(dst, t.length)
	} else {

	0x84, 0xd1, 0x3e, 0x56, 0xa0, 0x24, 0x9b, 0x73, 0xa2, 0x46, 0xef, 0x81, 0x02, 0x4b, 0xae, 0x44,
	0x26, 0x3a, 0xc0, 0x3b, 0x9f, 0xc5, 0x9d, 0xf8, 0xf8, 0xee, 0x39, 0xc1, 0x70, 0x29, 0x61, 0x13,
	0x25, 0xb1, 0xd2, 0x7e, 0xa8, 0x40, 0x12, 0xb0, 0x6a, 0xa7, 0x4c, 0x5f, 0x37, 0xb3, 0x3c, 0x1d,
	0x0b, 0x4f, 0x1f, 0x67, 0xe6, 0xfa, 0xcf, 0x88, 0x46, 0xf9, 0xc0, 0x7a, 0x22, 0x8d, 0xd6, 0xa0,

	// 480 bytes of a gzipped FileDescriptorProto
	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x8c, 0x93, 0x31, 0x8f, 0xd3, 0x30,
	0x18, 0x86, 0xeb, 0x1e, 0x91, 0x8a, 0xab, 0x4a, 0x25, 0x08, 0x29, 0xea, 0xe0, 0x46, 0xbd, 0x25,
	0xcb, 0xd9, 0xf4, 0x04, 0x08, 0xe9, 0xb6, 0x50, 0x09, 0x21, 0x81, 0xa8, 0x32, 0x30, 0x20, 0x06,
	0xdc, 0xd4, 0xe7, 0x9a, 0x26, 0x71, 0x64, 0x3b, 0x95, 0xba, 0xf1, 0x13, 0xf8, 0x53, 0x48, 0x1d,

	// 481 bytes of a gzipped FileDescriptorProto
	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x8c, 0x93, 0x31, 0x8f, 0xd3, 0x30,
	0x18, 0x86, 0xe3, 0x1e, 0x91, 0x8a, 0xab, 0x4a, 0x25, 0x08, 0x29, 0xaa, 0x74, 0x69, 0xd4, 0x5b,
	0x32, 0x70, 0x36, 0x3d, 0x01, 0x42, 0xba, 0x2d, 0x77, 0x12, 0x42, 0x02, 0x51, 0x32, 0x30, 0x20,
	0x06, 0x9c, 0xd4, 0x97, 0x9a, 0x26, 0x71, 0x64, 0x3b, 0x95, 0xba, 0xf1, 0x13, 0xf8, 0x51, 0x0c,

DATA andMask<>+0x28(SB)/8, $0x0000000000000000
DATA andMask<>+0x30(SB)/8, $0x00000000ffffffff
DATA andMask<>+0x38(SB)/8, $0x0000000000000000
DATA andMask<>+0x40(SB)/8, $0x000000ffffffffff
DATA andMask<>+0x48(SB)/8, $0x0000000000000000
DATA andMask<>+0x50(SB)/8, $0x0000ffffffffffff
DATA andMask<>+0x58(SB)/8, $0x0000000000000000
DATA andMask<>+0x60(SB)/8, $0x00ffffffffffffff
DATA andMask<>+0x68(SB)/8, $0x0000000000000000

	pals := []color.Palette{{
		color.RGBA{0x00, 0x00, 0x00, 0xff},
		color.RGBA{0x01, 0x00, 0x00, 0xff},
		color.RGBA{0x02, 0x00, 0x00, 0xff},
	}, {
		color.RGBA{0x00, 0x00, 0x00, 0xff},
		color.RGBA{0x00, 0x01, 0x00, 0xff},
	}, {
		color.RGBA{0x00, 0x00, 0x03, 0xff},
		color.RGBA{0x00, 0x00, 0x02, 0xff},
		color.RGBA{0x00, 0x00, 0x01, 0xff},
		color.RGBA{0x00, 0x00, 0x00, 0xff},
	}, {

// the same definition as [unicode.IsPrint]: letters, numbers, punctuation,
// symbols and ASCII space.
func IsPrint(r rune) bool {
	// Fast check for Latin-1
	if r <= 0xFF {
		if 0x20 <= r && r <= 0x7E {
			// All the ASCII is printable from space through DEL-1.
			return true
		}
		if 0xA1 <= r && r <= 0xFF {
			// Similarly for ¡ through ÿ...

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	0x14, 0xf7, 0xd6, 0x8e, 0xed, 0x1d, 0x87, 0xda, 0x9d, 0x82, 0xb4, 0xb2, 0xaa, 0xb5, 0xc9, 0x01,
	0x19, 0xa9, 0x9d, 0x25, 0x11, 0x54, 0x51, 0xc5, 0x25, 0x4b, 0x22, 0x14, 0x90, 0x9a, 0x68, 0x5a,
	0x43, 0xe1, 0x80, 0x34, 0xb6, 0xa7, 0xf6, 0x60, 0x7b, 0x66, 0xd9, 0x99, 0x4d, 0xf0, 0x8d, 0x3b,

DATA shifts<>+0x00(SB)/4, $0x00000000
DATA shifts<>+0x04(SB)/4, $0x00000000
DATA shifts<>+0x08(SB)/4, $0x00000000
DATA shifts<>+0x0c(SB)/4, $0x00000000

DATA shifts<>+0x10(SB)/4, $0xffffff0f
DATA shifts<>+0x14(SB)/4, $0xffffffff
DATA shifts<>+0x18(SB)/4, $0xffffffff
DATA shifts<>+0x1c(SB)/4, $0xffffffff

DATA shifts<>+0x20(SB)/4, $0xffff0f0e
DATA shifts<>+0x24(SB)/4, $0xffffffff
DATA shifts<>+0x28(SB)/4, $0xffffffff