private static boolean naturallyComparable(final Object f, final Object s) {
        return (f instanceof Comparable && s instanceof Comparable
                && (f.getClass().isInstance(s) || s.getClass().isInstance(f)))
                || f.equals(s);
    }
Return true if the two objects in the UNKNOWN type space are equal or comparable via their own natural Comparator.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/util/GremlinValueComparator.java