int bbtreedel(struct btree **tree, void *item, int (*cmp)(void *, void *));
int bbtreeput(struct btree **tree, void *item, int (*cmp)(void *, void *));
void *btreeget(struct btree *tree, void *key, int (*cmp)(void *, void *));
+void *btreeiter(struct btree *tree);
+void btreefree(struct btree *tree);
#define sizebuf(b, bs, rs, es, a) _sizebuf((void **)(void *)(b), (bs), (rs), (es), (a))
#define sizebuf2(b, rs, a) _sizebuf((void **)(void *)(&(b)), &(b ## size), (rs), sizeof(*(b)), (a))