pub type Iterator<T> |backing: &Any| = mut fn () -> Option<&T ref backing>

pub int Iterable<T> {
    ref fn iterator() -> Iterator<T>(&self)
}

fn main() {
    let nums: List<Int> = [1, 2, 3]
    let iterator: Iterator<Int> |backing = nums| = nums.iterator()
    let first: &Int ref nums = iterator().unwrap()
    let second: &Int ref nums = iterator().unwrap()
    let third: &Int ref nums = iterator().unwrap()
    println "${*first}, ${*second}, ${*third}"
}