anchor.diff:  ;                    (print (showdiff *first-impl* *second-impl* x)))))
   ;  (rdiff base modified 'ref 2))
   
  -(defun routeref-list (routeref-diff refmark)
  +(defun refnode-list (refdiff refmark)
     (let ((result))
       (maptree (lambda (leaf)
                  ;; Here, we need to coerce ATOMs into NIL. The MAPTREE
  
positive.code:              (:resolve () (if reserved (cons ref-mark route) subtree))
               (:cancel () (setf reserved nil)))))
  
  (defun rdiff (base modified refmark &optional (allowed-distance 0))
    (with-route (node r)
                (let (tmp)
  
negative.code:                ;; S-expressions other than ATOMs as leaves.
                 (if (not (atom leaf))
                   (car (push (cdr leaf) result))))
               refdiff
               :pred (lambda (x) (or (atom x) (eq (car x) refmark))))
      result))
  
  (defun lostnode-list (refdiff base refmark lostmark)
    (let ((refnodes (refnode-list refdiff refmark))
          result)
      (with-route (sub route) base
        (cond ((find route refnodes :test #'equal) (cons refmark route))
              ((find-if #'(start-with (route-normalize route) (route-normalize _))
                        refnodes)
               next-level)
              (t (push (cons lostmark route) result))))
        (nreverse result)))
  