assertTrue(TraversalHelper.isReversible(GraphTraversal.of().in().in()));
assertTrue(TraversalHelper.isReversible(GraphTraversal.of().inE().outV().outE().inV()));
assertTrue(TraversalHelper.isReversible(GraphTraversal.of().outE().has("since").inV()));
assertTrue(TraversalHelper.isReversible(GraphTraversal.of().outE().as("x")));
assertFalse(TraversalHelper.isReversible(new DefaultGraphTraversal().identity().as("a").outE().back("a")));
}