def _last_index(self, s):
        self.set_index(max(0, self._find_one_after_last_labeled_index() - 1))
def files(self):
        """Explicitly listed files or patterns or roots:
        if no patterns or .always(): empty list,
        if exact: list exact files,
        if not .anypats(): list all files and dirs,
        else: optimal roots"""
        return self._files