private void assert_g_v1_out(final Traversal<Vertex, Vertex> traversal) {
        printTraversalForm(traversal);
        int counter = 0;
        final Set<Vertex> vertices = new HashSet<>();
        while (traversal.hasNext()) {
            counter++;
            final Vertex vertex = traversal.next();
            vertices.add(vertex);
            assertTrue(vertex.value("name").equals("vadas") ||
                    vertex.value("name").equals("josh") ||
                    vertex.value("name").equals("lop"));
        }
        assertEquals(3, counter);
        assertEquals(3, vertices.size());
    }
@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/VertexTest.java