@Override
    public boolean remove(final Object traverser) {
        if (!(traverser instanceof Traverser.Admin))
            throw new IllegalArgumentException("The object to remove must be traverser");

        final boolean removed = super.remove(traverser);
        if (removed) index.removeMapping(indexingFunction.apply(((Traverser.Admin<S>) traverser).get()), traverser);
        return removed;
    }
Gets a collection of {@link Traverser} objects that contain the specified value.

@param k the key produced by the indexing function
@return
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/traverser/util/IndexedTraverserSet.java