is_sub_class_of
Use it like this:
- [ #is_/sub_class_of :: Class] or
- [ is_sub_class_of :: Class]
Relates a subclass to its super-class. Can be implemented with dedicated #Tags
Relation describes that: [ #has_/domain :: Class] ( #has_/name :: is_subclass_of) ( #has_/range :: Class)