anchor.diff:    (or (find-transition mold property-name)
         (aconsf (mold-transitions mold) property-name
                 (make-mold (mold-lineage mold)
  -                         (cons property-name (mold-properties mold))))))
  +                         (vector-cons property-name (mold-properties mold))))))
   
   (defun ensure-mold (parents properties)
     "Returns the mold with properties PROPERTIES of the mold for PARENTS,
  
positive.code:   "Also known as 'backend classes', molds are hidden caches which enable
  Sheeple to use class-based optimizations yet keep its dynamic power."
    (lineage     nil :read-only t :type lineage)
    (properties  nil :read-only t)
    (transitions nil :type '(list-of transition)))
  
  (defstruct (lineage
  
negative.code:   (check-list-type parents object)
    (or (find-mold parents)
        (setf (find-mold parents)
              (make-mold (make-lineage parents) (vector)))))
  
  (defun ensure-transition (mold property-name)
    "Returns the transition from MOLD indexed by PROPERTY-NAME, creating and
  