anchor.diff:                               (lambda (node) (set-property node stamp nil)))
         (let ( (cur-nodes (list startnode))
               cur-node  suc-nodes  )
  -        (while cur-nodes
  +        (loop :while cur-nodes :do
             (setq cur-node  (car cur-nodes)
                   cur-nodes (cdr cur-nodes))
   
  
positive.code: "
    ;;   (let ((elem-list (elements self))
    ;;         (result nil))
    ;;     (while elem-list
    ;;       (when (eq anElement (car elem-list))
    ;;         (setq result t)
    ;;         (setq elem-list nil))
  
negative.code:       (set-property startnode stamp t)
        (let ((cur-nodes (list startnode))
              cur-node)
          (loop :while cur-nodes :do
            (setq cur-node  (car cur-nodes)
                  cur-nodes (cdr cur-nodes))
            (dolist (edge (directed-edges-from-node self cur-node))
  