func retainSlash(s string) string {
	if s == "" {
		return s
	}
	return strings.TrimSuffix(s, SlashSeparator) + SlashSeparator
}

// pathsJoinPrefix - like pathJoin retains trailing SlashSeparator
// for all elements, prepends them with 'prefix' respectively.
func pathsJoinPrefix(prefix string, elem ...string) (paths []string) {
	paths = make([]string, len(elem))
	for i, e := range elem {
		paths[i] = pathJoin(prefix, e)
	}