struct Foo {
	x int
}

fn (a Foo) + (b Foo) Foo {
	return Foo{a.x + b.x}
}

fn (a Foo) % (b Foo) Foo {
	return Foo{a.x % b.x}
}

struct Indexed {
mut:
	values []int
}

fn (i Indexed) [] (index int) int {
	return i.values[index]
}

fn (mut i Indexed) []= (index int, value int) {
	i.values[index] = value
}