Ok, so what if something like this:

```rust
trait AtomicOps {
    type Target;

    fn fetch_and(...);
    // ....
}

impl AtomicOps for AtomicU16 {
    type Target = u16;
    // ....
}

trait AtomicType {
    type Target: AtomicOps;
}

trait AtomicType {
    type Target = u16;
}
```