键入'一棵树= | 空| 'a * 'a tree* 'a tree* 'a tree ref;; 的节点
我们希望将每个节点树的引用按顺序设置为下一个节点;
例如
Node (1, Node(2, Empty, Empty, ref Empty), Node(3, Empty, Empty, ref Empty), ref Empty) )
The result is:
Node (1, Node(2, Empty, Empty, content = {Node (1....) }).....