for (i = 0; i < arity; ++i) {
/* node is not in the head, but the predecessor is.
* (head or loop chain nodes are marked) */
DB((dbg, LEVEL_5, "... "));
for (i = 0; i < arity; ++i) {
/* node is not in the head, but the predecessor is.
* (head or loop chain nodes are marked) */
DB((dbg, LEVEL_5, "... "));