fn main() {
    let mut v = ~[1];
    v += ~[2];
    v += ~[3];
    v += ~[4];
    v += ~[5];
    assert (v[0] == 1);
    assert (v[1] == 2);
    assert (v[2] == 3);
    assert (v[3] == 4);
    assert (v[4] == 5);
}