anchor.diff:  	(error 'unbound-property))))
   
   (defun (setf property-value) (new-value sheep property-name)
  -  (if (std-metasheep-p sheep)
  +  (if (std-sheep-p sheep)
         (setf (std-property-value sheep property-name) new-value)
         (setf-property-value-using-metasheep 
          new-value (sheep-metasheep sheep) sheep property-name)))
  
positive.code:       (append obj-keys (mapcar #'available-properties (gethash 'parents sheep)))))))
  
  (defun available-cloneforms (sheep)
    (if (std-metasheep-p sheep)
        (std-available-cloneforms sheep)
        (available-cloneforms-using-metasheep (sheep-metasheep sheep) sheep)))
  (defun std-available-cloneforms (sheep)
  
negative.code: ;;;
  
  (defun property-value (sheep property-name)
    (if (std-sheep-p sheep)
        (std-property-value sheep property-name)
        (property-value-using-metasheep (sheep-metasheep sheep) sheep property-name)))
  (defun std-property-value (sheep property-name)
  