How does inheritance of __slots__ in subclasses actually work?

Question

In the Python data model reference section on slots there is a list of notes on using __slots__. I am thoroughly confused by the 1st and 6th items, because the

Answer 1

My understanding is as follows:

• class X has no __dict__ <-------> class X and its superclasses all have __slots__ specified

• in this case, the actual slots of the class are comprised from the union of __slots__ declarations for X and its superclasses; the behavior is undefined (and will become an error) if this union is not disjoint