+ attr_name = self.checked_class.to_save[-1]
+ attr = getattr(obj, attr_name)
+ if isinstance(attr, (int, float)):
+ new_attr = attr + 1
+ elif isinstance(attr, str):
+ new_attr = attr + '_'
+ elif isinstance(attr, bool):
+ new_attr = not attr
+ setattr(obj, attr_name, new_attr)