Generate the Fibonacci Sequence in Rust.

fib.rs

pub struct Fib {
    a: u32,
    b: u32,
    count: i32,
}

impl Fib {
    pub fn new(count: i32) -> Fib {
        Fib { a: 1, b: 1, count }
    }
}

impl Iterator for Fib {
    type Item = u32;

    fn next(&mut self) -> Option<Self::Item> {
        self.count -= 1;
        if self.count >= 0 {
            let curr = self.a;
            self.a = self.b;
            self.b = curr + self.a;

            Some(curr)
        } else {
            None
        }
    }
}

fn main() {
    let fib = Fib::new(10);
    for i in fib {
        println!("{}", i);
    }
}