Notes:

So how do singleton classes of singleton classes fit into ruby's class system?

It turns out that the superclass of a singleton class of a singleton class of a class is the singleton class of the class Class. This is true for all levels of singleton classes of singleton classes of classes.

The superclass of a singleton class of a singleton class of an object is the singleton class of the object's class, but for the third and higher levels, the superclass is the singleton class of the class Class.

This diagram is slightly simplified, as it doesn't take into account the Module class, but otherwise it should be accurate.

Any questions about singleton classes of singleton classes?