use Any
use Option

```doc
# Bitwise Xor

Values which wish to implement the `^` infix operator must implement this protocol.
```
protocol BitwiseXor, as: do
  ```doc
  Xor `self` and `other` together, returning an option.

  It is left up to the implementer to define when it should return `Some` or `None`.
  ```
  def or(self: Self, other: Any): Option
end