if start >= 0 {
			yield(s[start:len(s):len(s)])
		}
	}
}

// FieldsFuncSeq returns an iterator over subslices of s split around runs of
// Unicode code points satisfying f(c).
// The iterator yields the same subslices that would be returned by [FieldsFunc](s),
// but without constructing a new slice containing the subslices.
func FieldsFuncSeq(s []byte, f func(rune) bool) iter.Seq[[]byte] {
	return func(yield func([]byte) bool) {

	text := []byte("The quick brown fox")
	fmt.Println("Split on whitespace(similar to FieldsSeq):")
	for word := range bytes.FieldsFuncSeq(text, unicode.IsSpace) {
		fmt.Printf("%q\n", word)
	}

	mixedText := []byte("abc123def456ghi")
	fmt.Println("\nSplit on digits:")
	for word := range bytes.FieldsFuncSeq(mixedText, unicode.IsDigit) {
		fmt.Printf("%q\n", word)
	}

	// Output:

pkg bytes, func FieldsFuncSeq([]uint8, func(int32) bool) iter.Seq[[]uint8] #61901
pkg bytes, func FieldsSeq([]uint8) iter.Seq[[]uint8] #61901
pkg bytes, func Lines([]uint8) iter.Seq[[]uint8] #61901
pkg bytes, func SplitAfterSeq([]uint8, []uint8) iter.Seq[[]uint8] #61901
pkg bytes, func SplitSeq([]uint8, []uint8) iter.Seq[[]uint8] #61901
pkg crypto/cipher, func NewCFBDecrypter //deprecated #69445
pkg crypto/cipher, func NewCFBEncrypter //deprecated #69445

		if !slices.Equal(result, tt.a) {
			t.Errorf("FieldsFunc(%q) = %v, want %v", tt.s, a, tt.a)
		}

		result2 := sliceOfString(collect(t, FieldsFuncSeq([]byte(tt.s), pred)))
		if !slices.Equal(result2, tt.a) {
			t.Errorf(`collect(FieldsFuncSeq(%q)) = %v; want %v`, tt.s, result2, tt.a)
		}

		if string(b) != tt.s {
			t.Errorf("slice changed to %s; want %s", b, tt.s)
		}
		if len(tt.a) > 0 {