rn_newpair
t = rn_newpair(v_arg, b, nodes); tt = t->rn_l;
t = rn_newpair(rn_zeros, off, rnh->rnh_nodes);
t = rn_newpair(rn_zeros, off, base_nodes);
t = rn_newpair(v_arg, b, nodes);
*rn_newpair(void *, int, struct radix_node[2]),