Mixin class from third paries that has not __slot__

How use Mixin class that has not __slot__ from third parties?

From Issue 10796: Crash tests __slots__ when Mixin is not from trytond module - Tryton issue tracker

If you can not set __slot__ to all the inherited classes than you must explicitly say to not check with __no_slots__ = True. But this will have a performance cost as a dictionary will be created for each instance of this model.