class Traverser extends AbstractCentAlgorithm.Traverser {

        public Traverser(UserJob<Object> job) {
            super(job);
        }

        public Object closenessCentrality(Directions direction,
                                          String label,
                                          int depth,
                                          long degree,
                                          long sample,
                                          String sourceLabel,
                                          long sourceSample,
                                          String sourceCLabel,
                                          long topN) {<FILL_FUNCTION_BODY>}
    }

            assert depth > 0;
            assert degree > 0L || degree == NO_LIMIT;
            assert topN >= 0L || topN == NO_LIMIT;

            GraphTraversal<Vertex, Vertex> t = constructSource(sourceLabel,
                                                               sourceSample,
                                                               sourceCLabel);
            t = constructPath(t, direction, label, degree, sample,
                              sourceLabel, sourceCLabel);
            t = t.emit().until(__.loops().is(P.gte(depth)));
            t = filterNonShortestPath(t, true);

            /*
             * We use Marchiori's algorithm(sum of reciprocal of distances):
             *  .math("_-1").sack(Operator.div).sack().sum()
             * for Bavelas's algorithm:
             *  .math("_-1").sum().sack(Operator.div).sack()
             * see https://en.wikipedia.org/wiki/Closeness_centrality
             */
            GraphTraversal<Vertex, ?> tg;
            tg = t.group().by(__.select(Pop.first, "v").id())
                  .by(__.select(Pop.all, "v").count(Scope.local)
                        .math("_-1").sack(Operator.div).sack().sum());
            GraphTraversal<Vertex, ?> tLimit = topN(tg, topN);

            return this.execute(tLimit, tLimit::next);
        
<methods>public non-sealed void <init>() ,public java.lang.String category() ,public void checkParameters(Map<java.lang.String,java.lang.Object>) <variables>private static final Logger LOG