anchor.diff:          (curvalue (value current)))
       (cond ((< newvalue curvalue)
              (if (null (left current))
  -               (progn
  -                 (setf (left current) n)
  -                 (setf (parent n) current))
  +               (setf (left current) n (parent n) current)
                (insert-rec (left current) n)))
             ((> newvalue curvalue)
              (if (null (right current))
  -               (progn
  -                 (setf (right current) n)
  -                 (setf (parent n) current))
  +               (setf (right current) n (parent n) current)
                (insert-rec (right current) n)))
             (t nil))) ; no duplicates allowed
     T)
  
positive.code:                     (not (null (right delnode))))
                     (deleteInternalNode delnode))
                    (T (deleteNode delnode)))
              (- (size tree) 1)
              (if (not (null par))
                  (rotate tree par T)))))))
    T
  )
  
  
negative.code:   (let* ((par (parent n))
          (rig (right n))
          (riglef (left rig)))
        (setf (parent n) rig)
        (setf (right n) riglef)
        (setf (parent rig) par)
  