anchor.diff:  
   (defgeneric splay-step-with-parent (node parent))
   
  -(defmethod splay-step-with-parent ((node clump-binary-tree:node-with-parent)
  -				   (parent clump-binary-tree:node-with-parent))
  -  (if (eq node (clump-binary-tree:left parent))
  +(defmethod splay-step-with-parent ((node node-with-parent)
  +				   (parent node-with-parent))
  +  (if (eq node (left parent))
         (splay-step-with-right-parent node parent)
         (splay-step-with-left-parent node parent)))
   
  
positive.code:     (node parent grandparent))
  
  (defmethod splay-step-with-left-parent-and-left-grandparent
      ((node clump-binary-tree:node-with-parent)
       (parent clump-binary-tree:node-with-parent)
       (grandparent clump-binary-tree:node-with-parent))
    (clump-binary-tree:rotate-left grandparent)
    (clump-binary-tree:rotate-left parent)
    node)
  
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negative.code:     (node parent grandparent))
  
  (defmethod splay-step-with-left-parent-and-right-grandparent
      ((node node-with-parent)
       (parent node-with-parent)
       (grandparent node-with-parent))
    (rotate-left parent)
    (rotate-right grandparent)
    node)
  
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