2 Checks for usage of `_.filter(_).map(_)` that can be written more simply
6 Redundant code in the `filter` and `map` operations is poor style and
12 .filter(|n| n.checked_add(1).is_some())
13 .map(|n| n.checked_add(1).unwrap());
18 (0_i32..10).filter_map(|n| n.checked_add(1));