#pragma	lib	"libavl.a"#pragma src "/sys/src/libavl" typedef struct Avl	Avl;typedef struct Avltree	Avltree;typedef struct Avlwalk	Avlwalk; #pragma incomplete Avltree#pragma incomplete Avlwalk struct Avl{	Avl *p;	/* parent */	Avl *n[2];	/* children */	int bal;	/* balance bits */}; Avltree *mkavltree(int(*cmp)(Avl*, Avl*));void insertavl(Avltree *tree, Avl *new, Avl **oldp); Avl *lookupavl(Avltree *tree, Avl *key);void deleteavl(Avltree *tree, Avl *key, Avl **oldp);Avlwalk *avlwalk(Avltree *tree);Avl *avlnext(Avlwalk *walk);Avl	*avlprev(Avlwalk *walk);void endwalk(Avlwalk *walk);