### What it does
Checks for excessive
use of bools in structs.

### Why is this bad?
Excessive bools in a struct
is often a sign that it's used as a state machine,
which is much better implemented as an enum.
If it's not the case, excessive bools usually benefit
from refactoring into two-variant enums for better
readability and API.

### Example
```
struct S {
    is_pending: bool,
    is_processing: bool,
    is_finished: bool,
}
```

Use instead:
```
enum S {
    Pending,
    Processing,
    Finished,
}
```