#[derive(Debug)]
struct Fubar {
  x: Option<i32>,
  y: i32
}

impl Fubar {
  fn foo(&mut self) {
    for val in self.x {
        self.bar(val)
    }
  }
  fn bar(&mut self, n: i32) {
    self.y += n;
  }
}

fn main() {
    let mut fubar = Fubar { x: Some(1), y: 0, };
    fubar.foo();
    println!("{:?}", fubar)
}