### What it does
Checks for usage of `_.map_or(None, _)`.

### Why is this bad?
Readability, this can be written more concisely as
`_.and_then(_)`.

### Known problems
The order of the arguments is not in execution order.

### Example
```
opt.map_or(None, |a| Some(a + 1));
```

Use instead:
```
opt.and_then(|a| Some(a + 1));
```