parse.y:5433
static NODE*
arg_prepend(node1, node2)
    NODE *node1, *node2;
{
    switch (nodetype(node2)) {
      case NODE_ARRAY:
	return list_concat(NEW_LIST(node1), node2);

      case NODE_SPLAT:
	return arg_concat(node1, node2->nd_head);

      case NODE_BLOCK_PASS:
	node2->nd_body = arg_prepend(node1, node2->nd_body);
	return node2;

      default:
	rb_bug("unknown nodetype(%d) for arg_prepend", nodetype(node2));
    }
    return 0;			/* not reached */
}
