private void assertCommonA(final Traversal<Vertex, Map<String, String>> traversal) {
        final List<Map<String, String>> expected = makeMapList(2,
                "a", "marko", "b", "lop",
                "a", "marko", "b", "vadas",
                "a", "marko", "b", "josh",
                "a", "josh", "b", "ripple",
                "a", "josh", "b", "lop",
                "a", "peter", "b", "lop");
        checkResults(expected, traversal);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
@author Daniel Kuppitz (http://gremlin.guru)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/SelectTest.java