@Override
    public String toString() {
        return StringFactory.stepString(this, this.edgeTraversal.get(), this.pageRankProperty, this.times, new GraphFilter(this.computer));
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/traversal/step/map/PageRankVertexProgramStep.java