Methods for the instances of
X which are not found in
X itself are sought in
P, and its parent, and so on. Thus the mathematical notion of a set
P and a subset
X can modeled in this way.
Things which don't have instances have the empty class, called
Nothing as their parent. The parent of
Thing is
Thing itself (because every thing is a thing).
The entire structure of types and their parents can be displayed with
showStructure.