[ NoWrapper ]
public abstract int compare_with (Comparable other)
compares the object with an other object of the same type, returning <code class="literal">-1</code> if the
object is "less than" the other object, <code class="literal">0</code> if they're equal, or <code class="literal">1<
/code> if the object is "greater than" the other.
The function can assume that neither self or other will be null, and that
both have correct types. The function must be pure.