struct Count {
    c: u32,
}

impl Count {
    fn new() -> Count {
        Count { c: 0 }
    }
}

impl Iterator for Count {
    type Item = u32;
    fn next(&mut self) -> Option<Self::Item> {
        self.c += 1;
        if self.c < 6 {
            Some(self.c)
        } else {
            None
        }
    }
}

fn main() {
    let c = Count::new();
    for i in c {
        println!("{}", i)
    }

    let mut c2 = Count::new();

    for _i in (0..9) {
        if let Some(v) = c2.next() {
            println!("v: {}", v);
        } else {
            println!("none");
        }
    }
}