anchor.diff:                      (not (null (right delnode))))
                      (deleteInternalNode delnode))
                     (T (deleteNode delnode)))
  -            (- (size tree) 1)
  +            (decf (size tree))
               (if (not (null par))
  -                (rotate tree par T)))))))
  +                (rotate tree par T))))))
     T
   )
   
  
positive.code:   (print-tree tree)
    (terpri)
  
    (princ "Does the tree contain '999'? -> ")
    (if (contains tree 999)
        (princ "Yes")
  
negative.code:   (princ "done.")
    (terpri)
  
    (princ "Actual tree size:")
    (print (size tree))
    (terpri)
  
    (princ "Does the tree contain '-42'? -> ")
    (if (contains tree -42)
        (princ "Yes")
  