struct User {
    a int
    b int
}

struct Foo {
    a int
    b int
}

fn (u User) + () {
}

fn (u User) - (f Foo) User {
    return User{u.a - f.a, u.b-f.a}
}

fn main() {
    println(User{3, 4})
    println(User{3, 4} - Foo{3, 3})
}
