public static ComputerVertex mapReduce(final Vertex starVertex) {
        return new ComputerGraph(State.MAP_REDUCE, starVertex, Optional.empty()).starVertex;
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/util/ComputerGraph.java