func Integer.ToString() {
    var s = ""
    for x in 31^-1..0 {
        if this &&& (1 <<< x) != 0 {
            s += "1"
        } else if s != "" {
            s += "0"
        }
    }
    s
}

print("5 == \(5), 50 = \(50), 1000 = \(9000)")