enum MyOptionInt {
  Nothing,
  Value(i32),
}

fn print_opt(v: & MyOptionInt)
{
  match v {
    MyOptionInt::Nothing  => println!("Nothing!!!"),
    MyOptionInt::Value(n) => println!("{}", n),
  }
}

fn main()
{
  let     v1 = MyOptionInt::Nothing;
  let mut v2 = MyOptionInt::Value(666);

  print_opt(&v1);
  print_opt(&v2);
  v2 = v1;
  print_opt(&v2);
}