specific applicable initializer, if any. Slots without an initializer
are left uninitialized.
+ Slots are initialized in reverse-precedence order of their defining
+ classes; i.e., slots defined by a less specific superclass are
+ initialized earlier than slots defined by a more specific superclass.
+ Slots defined by the same class are initialized in the order in which
+ they appear in the class definition.
+
There are no standard keyword arguments; methods on subclasses are free
to introduce their own in the usual way.