if haveFastIndex {
			if j := bytealg.Index(s[i-last:], b[:n]); j >= 0 {
				return i + j - last
			}
		} else {
			// If bytealg.Index is not available a brute force search is
			// ~1.5-3x faster than Rabin-Karp since n is small.
			c0 := b[last]
			c1 := b[last-1] // There are at least 2 chars to match
		loop:
			for ; i < len(s); i++ {
				if s[i] == c0 && s[i-1] == c1 {
					for k := 2; k < n; k++ {

	{"foofyfoobarfoobar", "y", 4},
	{"oooooooooooooooooooooo", "r", -1},
	{"oxoxoxoxoxoxoxoxoxoxoxoy", "oy", 22},
	{"oxoxoxoxoxoxoxoxoxoxoxox", "oy", -1},
	// test fallback to Rabin-Karp.
	{"000000000000000000000000000000000000000000000000000000000000000000000001", "0000000000000000000000000000000000000000000000000000000000000000001", 5},
	// test fallback to IndexRune
	{"oxoxoxoxoxoxoxoxoxoxox☺", "☺", 22},

// This list is auto-generated, don't edit it manually.
// aaa : American Automobile Association, Inc.
// https://www.iana.org/domains/root/db/aaa.html
aaa

// aarp : AARP
// https://www.iana.org/domains/root/db/aarp.html
aarp

// abb : ABB Ltd
// https://www.iana.org/domains/root/db/abb.html
abb

// abbott : Abbott Laboratories, Inc.
// https://www.iana.org/domains/root/db/abbott.html

64-b.it
6g.in
7.azurestaticapps.net
7.bg
8.bg
9.bg
9guacu.br
a.bg
a.prod.fastly.net
a.se
a.ssl.fastly.net
a2hosted.com
aa.no
aaa
aaa.pro
aaa.vodka
aarborte.no
aarp
ab.ca
abashiri.hokkaido.jp
abb
abbott
abbvie
abc
abc.br
abeno.osaka.jp
abiko.chiba.jp
abira.hokkaido.jp
abkhazia.su
able
abo.pa
abogado
abr.it
abruzzo.it

64-b.it
6g.in
7.azurestaticapps.net
7.bg
8.bg
9.bg
9guacu.br
a.bg
a.prod.fastly.net
a.se
a.ssl.fastly.net
a2hosted.com
aa.no
aaa
aaa.pro
aaa.vodka
aarborte.no
aarp
ab.ca
abashiri.hokkaido.jp
abb
abbott
abbvie
abc
abc.br
abeno.osaka.jp
abiko.chiba.jp
abira.hokkaido.jp
abkhazia.su
able
abo.pa
abogado
abr.it
abruzzo.it