anchor.diff:  
   ;; --
   
  -;; FIXME: Test DEFSINGLETON with a SINGLETON superclass of a direct
  -;; superclass not repreenting a SINGLETON
  +;; FIXME: Test DEFSINGLETON with a superclass not being of a metatype
  +;; SINGLETON, but such that a direct superclass of that class is of
  +;; metatype SINGLETON
   
   (eval-when ()
   
  
positive.code:   (subtypep (make-instance 'x-b) 'x-a)
    ;; FIXME while => NIL, T
  
    (subtypep (find-class 'x-b) 'x-a)
    ;; => T, T
    ;; should be same, with or without the added SHARED-INITIALIZE
    ;; as it's consistent onto CLOS
  
  
  ;; -- test the new SHARED-INITIALIZE method with the original DEFSINGLETON macro
  
negative.code: ;; NB: To produce a suclass C2 of a class C1, such that C2 is both an
  ;; instance typep C1 and a subtype of C1 ...
  ;;
  ;; one may define MAKE-INSTANCE => CREATE-IMPLICIT-SUBCLASS
  ;; via ALLOCATE-INSTANCE
  ;;
  ;; This, albeit, may seem to pose some difficulty for typing in the
  