def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def _exit_modes_beyond(self, thisMode):
        if not self.modeList: return
        while len(self.modeList) > thisMode + 1: 
            self.modeList.pop().exit()