mod fib;

    println!("Hello, world!");

	let n = 90;
	let result = fib::fib_iter(n).unwrap();
  println!("Fib: {result}");

struct FibIter {
    current: usize,
    next: usize,
}
impl Default for FibIter {
    fn default() -> FibIter {
        FibIter {
            current: 1,
            next: 1,
        }
    }
}
impl Iterator for FibIter {
    type Item = usize;
    fn next(&mut self) -> Option<Self::Item> {
			let current = self.current;
			self.current = self.next;
			self.next += current;
			Some(current)
    }
}
pub fn fib_iter(n: usize) -> Option<usize> {
	FibIter::default().nth(n)
}