interface Rect {
    width  u32
    height u32
}

struct Square {
    side   u32
    width  u32
    height u32
}

fn test_main() {
    squares := [Square{
        side:   5
        width:  5
        height: 5
    }]
    rects := squares.map(Rect(it))

    assert rects.str() == '[Rect(Square{
    side: 5
    width: 5
    height: 5
})]'
}

fn test_fixed_array() {
    squares := [Square{
        side:   5
        width:  5
        height: 5
    }]!
    rects := squares.map(Rect(it))
}