Method: (NODE-INSERT BINARY-TREE-NODE T T T)

Source

(defmethod node-insert ((node binary-tree-node) k val tree)
  (with-slots (key value left right) node
    (cond ((comp-= k key) (setf value val))
	  ((comp-< k key) (setf left(node-insert left k val tree)))
	  (t (setf right (node-insert right k val tree))))
    node))