RB_DUPLICATE
rbtree = rb_create(RB_ALLOC, RB_DUPLICATE);
return insert_many(RB_NOALLOC, RB_DUPLICATE);
return remove_many(RB_NOALLOC, RB_DUPLICATE);
if (rbtree->insert != RB_DUPLICATE)
if (key == parent->key && rbtree->insert != RB_DUPLICATE) {