public Traversal.Admin<S, E> getValueTraversal() {
        return valueTraversal;
    }
A map step that returns the merger of the traverser and the provided arguments without duplicates. This is commonly
known as a union.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/MergeStep.java