private static Direction getDirection(final String direction) {
        if (direction.equals("from")) return Direction.OUT;
        if (direction.equals("to")) return Direction.IN;
        return Direction.valueOf(direction);
    }
Reuse edge triplet syntax for VertexProperty: vp[vertexName-key->value]
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/features/StepDefinition.java