@Setup(Level.Invocation)
    public void prepare() {
        graph = TinkerGraph.open();
        g = graph.traversal();
    }
Graph write and update benchmarks extend {@code AbstractGraphMutateBenchmark}.  {@code AbstractGraphMutateBenchmark}
runs setup once per invocation so that benchmark measurements are made on an empty {@link TinkerGraph}.  This approach
was taken to isolate the tested method from the performance side effects of unbounded graph growth.

@author Ted Wilmes (http://twilmes.org)
gremlin-tools/gremlin-benchmark/src/main/java/org/apache/tinkerpop/benchmark/util/AbstractGraphMutateBenchmark.java