func (r *Reader) openReadDir(dir string) []fileListEntry {
	files := r.fileList
	i, _ := slices.BinarySearchFunc(files, dir, func(a fileListEntry, dir string) int {
		idir, _, _ := split(a.name)
		if dir != idir {
			return strings.Compare(idir, dir)
		}
		// find the first entry with dir
		return +1
	})
	j, _ := slices.BinarySearchFunc(files, dir, func(a fileListEntry, dir string) int {
		jdir, _, _ := split(a.name)

		// a not equal b
	}
}

func ExampleCompare_search() {
	// Binary search to find a matching byte slice.
	var needle []byte
	var haystack [][]byte // Assume sorted
	_, found := slices.BinarySearchFunc(haystack, needle, bytes.Compare)
	if found {
		// Found it!
	}
}

func ExampleContains() {
	fmt.Println(bytes.Contains([]byte("seafood"), []byte("foo")))