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 remove_item(self, item):
    if (self._locker.is_unlocked("prevent_removal_below_min_size")
        and len(self._items) == self._min_size):
      return