anchor.diff:  
   
   (defun dll-append (&rest dlls)
  -  (apply (function dll-nconc) (mapcar (function dll-copy) dlls)))
  -
  -
  -(defun dll-nconc (&rest dlls)
  -  "
  -PRE:   No dll appears twice in dlls.
  -DO:    Extract the nodes from all but the first dll,
  -       and append them to that first dll.
  +  "
  +DO:     Appends the elements in all the DLLS into a single dll.
  +        The DLLs are not modified.
  +RETURN: A new dll with all the elements in DLLS.
   "
     (if (null dlls)
         (make-dll)
  -      (do ((result  (do ((dll (pop dlls) (pop dlls)))
  -                        ((%dll-first dll) dll)))
  -           (dlls dlls (cdr dlls))
  -           (dll))
  -          ((null dlls) result)
  -        (setf dll (car dlls))
  +      (apply (function dll-nconc) (mapcar (function dll-copy) dlls))))
  +
  +
  +(defun dll-nconc (first-dll &rest DLLS)
  +  "
  +PRE:   No dll appears twice in (CONS FIRST-DLL DLLS).
  +DO:    Extract the nodes from all but the FIRST-DLL,
  +       and append them all to that FIRST-DLL.
  +"
  +  (if (null dlls)
  +      first-dll
  +      (dolist (dll (rest dlls) first-dll)
           (let ((first (%dll-first dll)))
             (unless (null first)
  -            (setf (dll-node-previous first) (%dll-last result)
  -                  (dll-node-next (%dll-last result)) first
  -                  (%dll-last result) (%dll-last dll)
  +            (setf (dll-node-previous first) (%dll-last first-dll)
  +                  (dll-node-next (%dll-last first-dll)) first
  +                  (%dll-last first-dll) (%dll-last dll)
                     (%dll-first dll) nil
                     (%dll-last dll) nil))))))
   
  
positive.code: 
  
  (defun dll (&rest list)
    (let ((dlist (make-dll))
          (current nil))
      (map nil (lambda (item) (setf current (dll-append dlist current item))) list)
      dlist))
  
  (defun dll-first-node (dlist) (%dll-first dlist))
  (defun dll-last-node  (dlist) (%dll-last dlist))
  
negative.code: (defun dll-delete-nth (index dlist)
    (dll-extract-node dlist (dll-node-nth index dlist)))
  
  
  ;;;; THE END ;;;;
  