2 let _ = (0..4).filter_map(|x| if x > 1 { Some(x) } else { None });
3 let _ = (0..4).filter_map(|x| { if x > 1 { return Some(x); }; None });
4 let _ = (0..4).filter_map(|x| match x {
9 let _ = (0..4).filter_map(|x| Some(x + 1));
11 let _ = (0..4).filter_map(i32::checked_abs);