def _last_index(self, s):
        self.set_index(max(0, self._find_one_after_last_labeled_index() - 1))
def serialize(self, value, display=False):
        if value is True:
            return "true"
        elif value in (False, None):
            return "false"
        else:
            raise ValueError(f"{value!r} is not a boolean")