return splitSeq(s, sep, len(sep))
}

// FieldsSeq returns an iterator over subslices of s split around runs of
// whitespace characters, as defined by [unicode.IsSpace].
// The iterator yields the same subslices that would be returned by [Fields](s),
// but without constructing a new slice containing the subslices.
func FieldsSeq(s []byte) iter.Seq[[]byte] {
	return func(yield func([]byte) bool) {
		start := -1