outrun/outrun-core/lib/integer.run

```doc
# Integer

This protocol defines all the protocols and functions required for a value to masquerade as an integer.

For the concrete implementation see `Outrun.Core.Integer`.
```
protocol Integer,
  requires:
    AbsoluteValue + Addition + BitwiseAnd + BitwiseOr + BitwiseXor + Division +
    Equality + Exponentiation + GreaterOrEqual + Greater + LessOrEqual + Less +
    Modulus + Multiplication + Negation + ShiftLeft + ShiftRight + Subtraction,
  as: do
    ```doc
    Returns whether the value of `self` is greater than zero.
    ```
    def positive?(self: Self): Boolean

    ```doc
    Returns whether the value of `self` is zero.
    ```
    def zero?(self: Self): Boolean

    ```doc
    Returns whether the value of `self` is less than zero.
    ```
    def negative?(self: Self): Boolean
  end