@Override
    public String toString() {
        return StringFactory.stepString(this, this.pop, this.keyTraversal, this.selectTraversal);
    }
@author Daniel Kuppitz (http://gremlin.guru)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/TraversalSelectStep.java