### What it does
Checks for usage of `_.as_ref().map(Deref::deref)` or it's aliases (such as String::as_str).

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

### Example
```
opt.as_ref().map(String::as_str)
```
Can be written as
```
opt.as_deref()
```