@Override
    public RangeGlobalStep<S> clone() {
        final RangeGlobalStep<S> clone = (RangeGlobalStep<S>) super.clone();
        clone.counter = new AtomicLong(0l);
        return clone;
    }
@author Bob Briody (http://bobbriody.com)
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/filter/RangeGlobalStep.java