SLL_INSERT
err = SLL_INSERT(node->opened, next, fc);
SLL_INSERT(ns->queries, qnext, qn);
SLL_INSERT(qn->opened, next, c);
SLL_INSERT(node->opened, next, c);
err = SLL_INSERT(node->opened, next, fc);
err = SLL_INSERT(ns->nodes, nlnext, n);
err = SLL_INSERT(dir->children, next, n);
SLL_INSERT(node->opened, next, c);