object.c:922
static VALUE
rb_obj_methods(argc, argv, obj)
    int argc;
    VALUE *argv;
    VALUE obj;
{
  retry:
    if (argc == 0) {
	VALUE args[1];

	args[0] = Qtrue;
	return rb_class_instance_methods(1, args, CLASS_OF(obj));
    }
    else {
	VALUE recur;

	rb_scan_args(argc, argv, "1", &recur);
	if (RTEST(recur)) {
	    argc = 0;
	    goto retry;
	}
	return rb_obj_singleton_methods(argc, argv, obj);
    }
}
