// code point satisfying f(c), or -1 if none do.
func LastIndexFunc(s []byte, f func(r rune) bool) int {
	return lastIndexFunc(s, f, true)
}

// indexFunc is the same as IndexFunc except that if
// truth==false, the sense of the predicate function is
// inverted.
func indexFunc(s []byte, f func(r rune) bool, truth bool) int {
	start := 0
	for start < len(s) {
		wid := 1
		r := rune(s[start])
		if r >= utf8.RuneSelf {

	if x == o {
		return false
	}
	// Prefer newest modtime.
	if x.ModTime != o.ModTime {
		return x.ModTime > o.ModTime
	}

	// The following doesn't make too much sense, but we want sort to be consistent nonetheless.
	// Prefer lower types
	if x.Type != o.Type {
		return x.Type < o.Type
	}
	// Consistent sort on signature

		}
	}

	n = len(b0) - len(b)
	switch {
	case err == io.EOF:
		return n, errMissData // Less data in dense file than sparse file
	case err != nil:
		return n, err
	case sr.logicalRemaining() == 0 && sr.physicalRemaining() > 0:
		return n, errUnrefData // More data in dense file than sparse file
	case finished:
		return n, io.EOF
	default:
		return n, nil
	}
}