anchor.diff:          (awhen (some (fun (find-transition start-node _)) path)
             (find-node-by-transitions it path)))))
   
  -(defun find-mold (parents)
  -  (check-list-type parents object)
  -  (values (gethash parents *molds*)))
  -
  -(defun (setf find-mold) (mold parents)
  -  (check-list-type parents object)
  -  (check-type mold mold)
  -  (setf (gethash parents *molds*) mold))
  -
   (defun find-mold-node (parents properties)
     "Searches the mold cache for one with parents PARENTS and properties PROPERTIES,
   returning that mold if found, or NIL on failure."
  
positive.code:   "Maps parent lists to their corresponding molds. This is the global entry
  point to Sheeple's backend class system.")
  
  ;;;
  ;;; Transitions
  ;;;
  
negative.code:   (check-type node node)
    (check-type property-name property-name)
    (or (find-transition node property-name)
        (aconsf (%node-transitions node) property-name
                (make-node :mold (%node-mold node)
                           :properties (cons property-name
                                             (%node-properties node))))))
  
  (defun ensure-mold (parents properties)
    (or (find-mold parents properties)
  