SPLAY_MIN
ins = SPLAY_MIN(tree, &root);
while ((id = SPLAY_MIN(xarray_tree, &xa->xa_tree))) {
while ((id = SPLAY_MIN(idr_tree, &idr->tree))) {
for ((x) = SPLAY_MIN(name, head); \
curr = SPLAY_MIN(_dict, &d->dict);
curr = SPLAY_MIN(_dict, &d->dict);
curr = SPLAY_MIN(_tree, &t->tree);
curr = SPLAY_MIN(_tree, &t->tree);