struct St {
mut:
    x int
    // data to be shared
}

fn (shared b St) g(shared c St) {
    lock b {
        b.x = 100
    }
}

fn foo(shared b St) {
    lock b {
        b.x = 101
    }
}

fn main() {
    shared a := St{
        x: 10
    }
    spawn a.g(a)
    spawn foo(a)

    rlock a {
        println(a.x)
    }
}