### What it does
Checks for usage of `_.filter(_).map(_)` that can be written more simply
as `filter_map(_)`.

### Why is this bad?
Redundant code in the `filter` and `map` operations is poor style and
less performant.

### Example
```
(0_i32..10)
    .filter(|n| n.checked_add(1).is_some())
    .map(|n| n.checked_add(1).unwrap());
```

Use instead:
```
(0_i32..10).filter_map(|n| n.checked_add(1));
```