128, 0, 0, // headerFields, bg, aspect (10)
	0, 0, 0, 1, 1, 1, // color table and graphics control (13)
	0x21, 0xf9, 0x04, 0x00, 0x00, 0x00, 0xff, 0x00, // (19)
	// frame 1 (0,0 - 1,1)
	0x2c,
	0x00, 0x00, 0x00, 0x00,
	0x01, 0x00, 0x01, 0x00, // (32)
	0x00,
	0x02, 0x02, 0x4c, 0x01, 0x00, // lzw pixels
	// trailer
	0x3b,
}

func try(t *testing.T, b []byte, want string) {

		// is not needed.
		e.buf[0] = 0x00
		e.buf[1] = 0x00 // Background Color Index.
		e.buf[2] = 0x00 // Pixel Aspect Ratio.
		e.write(e.buf[:3])
	}

	// Add animation info if necessary.
	if len(e.g.Image) > 1 && e.g.LoopCount >= 0 {
		e.buf[0] = 0x21 // Extension Introducer.
		e.buf[1] = 0xff // Application Label.
		e.buf[2] = 0x0b // Block Size.
		e.write(e.buf[:3])

		},
		{
			in:   FromInt32(math.MaxUint8 + 1), // min positive integer representable in three bytes
			want: []byte{0x19, 0x01, 0x00},
		},
		{
			in:   FromInt32(math.MaxUint16), // max positive integer representable in three bytes
			want: []byte{0x19, 0xff, 0xff},
		},
		{
			in:   FromInt32(math.MaxUint16 + 1), // min positive integer representable in five bytes
			want: []byte{0x1a, 0x00, 0x01, 0x00, 0x00},

			recognizes: true,
		},
		{
			in:         []byte{0xff, 0xff, 0xff},
			recognizes: false,
		},
		{
			in:         []byte{0xd9, 0xd9, 0xf7, 0x01, 0x02, 0x03},
			recognizes: true,
		},
		{
			in:         []byte{0xff, 0xff, 0xff, 0x01, 0x02, 0x03},
			recognizes: false,
		},
	} {
		t.Run(hex.EncodeToString(tc.in), func(t *testing.T) {
			s := NewSerializer(nil, nil)

	//	slice "recursiveSlice" id=106
	//		elem id=106
	// }
	data := []byte{
		0x1d, 0xff, 0xd3, 0x02, 0x01, 0x01, 0x0e, 0x72,
		0x65, 0x63, 0x75, 0x72, 0x73, 0x69, 0x76, 0x65,
		0x53, 0x6c, 0x69, 0x63, 0x65, 0x01, 0xff, 0xd4,
		0x00, 0x01, 0xff, 0xd4, 0x00, 0x00, 0x07, 0xff,
		0xd4, 0x00, 0x02, 0x01, 0x00, 0x00,
	}
	dec := NewDecoder(bytes.NewReader(data))
	// Issue 10415: This caused infinite recursion.

	//     position is "position 1") does not have hexadecimal value 0x01,
	//     output "inconsistent" and stop.
	psLen := emLen - hLen - sLen - 2
	for _, e := range db[:psLen] {
		if e != 0x00 {
			return ErrVerification
		}
	}
	if db[psLen] != 0x01 {
		return ErrVerification
	}

	// 11.  Let salt be the last sLen octets of DB.
	salt := db[len(db)-sLen:]

	{"0:0:0:0:0000:ffff:127.1.2.3", IPv4(127, 1, 2, 3)},
	{"0:0:0:0::ffff:127.1.2.3", IPv4(127, 1, 2, 3)},

	{"2001:4860:0:2001::68", IP{0x20, 0x01, 0x48, 0x60, 0, 0, 0x20, 0x01, 0, 0, 0, 0, 0, 0, 0x00, 0x68}},
	{"2001:4860:0000:2001:0000:0000:0000:0068", IP{0x20, 0x01, 0x48, 0x60, 0, 0, 0x20, 0x01, 0, 0, 0, 0, 0, 0, 0x00, 0x68}},

	{"-0.0.0.0", nil},
	{"0.-1.0.0", nil},
	{"0.0.-2.0", nil},
	{"0.0.0.-3", nil},
	{"127.0.0.256", nil},
	{"abc", nil},

	IPv6loopback               = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
	IPv6interfacelocalallnodes = IP{0xff, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
	IPv6linklocalallnodes      = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
	IPv6linklocalallrouters    = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x02}
)

// IsUnspecified reports whether ip is an unspecified address, either

	gcDisposalMethodMask  = 7 << 2
)

// Disposal Methods.
const (
	DisposalNone       = 0x01
	DisposalBackground = 0x02
	DisposalPrevious   = 0x03
)

// Section indicators.
const (
	sExtension       = 0x21
	sImageDescriptor = 0x2C
	sTrailer         = 0x3B
)

// Extensions.
const (
	eText           = 0x01 // Plain Text
	eGraphicControl = 0xF9 // Graphic Control
	eComment        = 0xFE // Comment

	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},
	}, {