@Override
    public boolean offer(final Traverser.Admin<S> traverser) {
        return this.add(traverser);
    }
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