@Test
    public void shouldGetStepsOfAssignableClassRecursivelyMultipleTypes() {
        final Traversal.Admin<?,?> traversal = __.V().repeat(__.out()).project("x").by(out().in().fold()).asAdmin();
        final List<Step<?,?>> steps = TraversalHelper.getStepsOfAssignableClassRecursively(traversal, VertexStep.class, FoldStep.class);
        assertEquals(4, steps.size());
        assertEquals(3, steps.stream().filter(s -> s instanceof VertexStep).count());
        assertEquals(1, steps.stream().filter(s -> s instanceof FoldStep).count());
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/process/traversal/util/TraversalHelperTest.java