Example:
```
- cargo fmt --emit files
+ cargo fmt -- --emit files
```
Options:
| Flag |Description| Nightly Only |
|:---:|:---:|:---:|
| files | overwrites output to files | No |
- | stdout | writes output to stdout | No |
+ | stdout | writes output to stdout | No |
| coverage | displays how much of the input file was processed | Yes |
| checkstyle | emits in a checkstyle format | Yes |