struct Foo {
    bar shared struct {
    mut:
        foo int
        bar int
    }
    baz shared int
}

fn test_main() {
    assert Foo{}.str() == 'Foo{
    bar: struct {
        foo: 0
        bar: 0
    }
    baz: 0
}'
    mut t := Foo{}
    lock t.bar {
        t.bar.foo = 1
        t.bar.bar = 2
    }
    rlock t.bar {
        assert t.bar.foo + t.bar.bar == 3
    }
}