@define fn(a ...)
{
	printf("%a -> ", a);
	return length(a);
}

printf("%a\n", apply(fn, []));
printf("%a\n", apply(fn, [1]));
printf("%a\n", apply(fn, [1, 2]));
printf("%a\n", apply(fn, [1, 2, 3]));

printf("%a\n", apply(fn, 1, []));
printf("%a\n", apply(fn, 1, [2]));
printf("%a\n", apply(fn, 1, [2, 3]));
printf("%a\n", apply(fn, 1, 2, [3]));
printf("%a\n", apply(fn, 1, 2, [3, 4]));
printf("%a\n", apply(fn, 1, 2, [3, 4, 5]));