public default boolean isHalted() {
            return getStepId().equals(HALT);
        }
If the traverser has "no future" then it is done with its lifecycle.
This does not mean that the traverser is "dead," only that it has successfully passed through a
{@link Traversal}.

@return Whether the traverser is done executing or not
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/Traverser.java