private static void vertexPropertyChecks(final Vertex v) {
        assertEquals(2, v.keys().size());
        assertTrue(v.keys().contains(VertexProgramR.PROPERTY_IN));
        assertTrue(v.keys().contains(VertexProgramR.PROPERTY_OUT));
        assertEquals(1, IteratorUtils.count(v.values(VertexProgramR.PROPERTY_IN)));
        assertEquals(1, IteratorUtils.count(v.values(VertexProgramR.PROPERTY_OUT)));
    }
This is only configurable for the purpose of testing. In a real-world VP this would be a bad pattern.
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/computer/GraphComputerTest.java