anchor.diff:        ;; as may extend SINGLETON. In a future revision, this concern may
         ;; be addressed with a manner of initialization argument mangling
         ;; onto SHARED-INITIALIZE (SINGLETON T)
  +      ;;
  +      ;; NB: This should be considered again, in light of the
  +      ;; PROTOTYPE-CLASS proposal, as described -- in something of a
  +      ;; rough sketch reagard -- at the end of this source file.
  +      ;;
  +      ;; This macro may subsequently be updated to not use DEFCLASS at
  +      ;; all.
  +      ;;
  +      ;; It should provide an analogous behvior to DEFCLASS, in every
  +      ;; portable regard. Note e.g during SB-PCL DEFCLASS
  +      ;; - SB-KERNEL::%COMPILER-DEFCLASS in the compiler environment
  +      ;;   - Can this be approximated with a compile-time DEFTYPE ?
  +      ;; - SB-PCL::LOAD-DEFCLASS in normal top-level evaluation
         (multiple-value-bind (%metaclass %params)
  +          ;; NB: This does not check to ensure that any specified
  +          ;; metaclass is a subtype of SINGLETON
  +          ;;
  +          ;; NB: This metaclass support might be summarily removed, in
  +          ;; lieu of a SINGLETON-PROTOTYPE semntics - if not supplanted
  +          ;; with a :PROTOTYPE-METACLASS semantics
             (compute-metaclass params)
  +
  +        ;; FIXME: Prepend the singleton prototype class to %SUPERCLASSES
  +        ;; ... in effect, as this may have to abandon DEFCLASS
           `(defclass ,name ,%superclasses
              ,slots
              ,%metaclass
  
positive.code: 
  (class-direct-slots (find-class 'singleton-2))
  
  
  )
  
negative.code: ;; => T, T, T, T
  
  
  (class-slots (find-class 'singleton-1))
  
  (class-direct-slots (find-class 'singleton-1))
  
  (defsingleton singleton-2 (singleton-1)
    ((sl-c)))
  