{1e23, 'e', 17, "9.99999999999999916e+22"},
		{1e23, 'f', 17, "99999999999999991611392.00000000000000000"},
		{1e23, 'g', 17, "9.9999999999999992e+22"},

		{1e23, 'e', -1, "1e+23"},
		{1e23, 'f', -1, "100000000000000000000000"},
		{1e23, 'g', -1, "1e+23"},

		{below1e23, 'e', 17, "9.99999999999999748e+22"},
		{below1e23, 'f', 17, "99999999999999974834176.00000000000000000"},
		{below1e23, 'g', 17, "9.9999999999999975e+22"},

	{"1x", "0", ErrSyntax},
	{"1.1.", "0", ErrSyntax},
	{"1e23", "1e+23", nil},
	{"1E23", "1e+23", nil},
	{"100000000000000000000000", "1e+23", nil},
	{"1e-100", "1e-100", nil},
	{"123456700", "1.234567e+08", nil},
	{"99999999999999974834176", "9.999999999999997e+22", nil},
	{"100000000000000000000001", "1.0000000000000001e+23", nil},
	{"100000000000000008388608", "1.0000000000000001e+23", nil},

Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8,fr-CH;q=0.6
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
COOKIE: __utma=000000000.0000000000.0000000000.0000000000.0000000000.00; __utmb=000000000.0.00.0000000000; __utmc=000000000; __utmz=000000000.0000000000.00.0.utmcsr=code.google.com|utmccn=(referral)|utmcmd=referral|utmcct=/p/go/issues/detail
Non-Interned: test

`, "\n", "\r\n", -1)

000002c0  95 fd 37 14 8c 34 f3 07  10 f8 dd e3 66 28 1c b2  |..7..4......f(..|
000002d0  a0 14 03 03 00 01 01 16  03 03 00 40 00 00 00 00  |...........@....|
000002e0  00 00 00 00 00 00 00 00  00 00 00 00 6c b8 ab 0b  |............l...|
000002f0  c1 2d 2f 4e d2 25 14 96  24 c6 18 97 82 93 1c 1b  |.-/N.%..$.......|
00000300  b4 ca 77 8b 17 7c cf 08  ca 06 e2 ef f3 97 6a 31  |..w..|........j1|

	"750486563e-38",
	"3752432815e-39",
	"75224575729e-45",
	"459926601011e+15",

	// Constants plundered from strconv/atof_test.go.

	"0",
	"1",
	"+1",
	"1e23",
	"1E23",
	"100000000000000000000000",
	"1e-100",
	"123456700",
	"99999999999999974834176",
	"100000000000000000000001",
	"100000000000000008388608",
	"100000000000000016777215",
	"100000000000000016777216",
	"-1",
	"-0.1",

 *   <dt>From the IPv6 reserved documentation prefix ({@code 2001:db8::/32}), {@code "2001:db8::1"}.
 *   <dd>{@code 20 01 0d b8 00 00 00 00 00 00 00 00 00 00 00 01}
 *   <dt>An IPv6 "IPv4 compatible" (or "compat") address, {@code "::192.168.0.1"}.
 *   <dd>{@code 00 00 00 00 00 00 00 00 00 00 00 00 c0 a8 00 01}
 *   <dt>An IPv6 "IPv4 mapped" address, {@code "::ffff:192.168.0.1"}.
 *   <dd>{@code 00 00 00 00 00 00 00 00 00 00 ff ff c0 a8 00 01}

 *   <dt>From the IPv6 reserved documentation prefix ({@code 2001:db8::/32}), {@code "2001:db8::1"}.
 *   <dd>{@code 20 01 0d b8 00 00 00 00 00 00 00 00 00 00 00 01}
 *   <dt>An IPv6 "IPv4 compatible" (or "compat") address, {@code "::192.168.0.1"}.
 *   <dd>{@code 00 00 00 00 00 00 00 00 00 00 00 00 c0 a8 00 01}
 *   <dt>An IPv6 "IPv4 mapped" address, {@code "::ffff:192.168.0.1"}.
 *   <dd>{@code 00 00 00 00 00 00 00 00 00 00 ff ff c0 a8 00 01}

	}
	return ret
}

// StringExpanded is like [Addr.String] but IPv6 addresses are expanded with leading
// zeroes and no "::" compression. For example, "2001:db8::1" becomes
// "2001:0db8:0000:0000:0000:0000:0000:0001".
func (ip Addr) StringExpanded() string {
	switch ip.z {
	case z0, z4:
		return ip.String()
	}

	const size = len("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")
	ret := make([]byte, 0, size)