pub struct RectIter {
    points: Vec<(f64, f64)>,
    idx: usize,
}

impl Iterator for RectIter {
    type Item = (f64, f64);

    /*
     * The reason why is mutable (&mut self), is that the only way to iterate through something,
     * is that the underline iterator has to be mutable, bacause you have to be able to change
     * the state until you are at the end.
     */
    fn next(&mut self) -> Option<Self::Item> {
        if self.idx >= self.points.len() {
            return None;
        }

        let point = self.points[self.idx];
        self.idx += 1;

        return Some(point);
    }
}