@Override
    protected Traverser.Admin<E> processNextStart() {
        final Traverser.Admin<S> traverser = this.starts.next();
        return traverser.split(this.map(traverser), this);
    }
A type of {@link MapStep} class which will transform the object of one {@link Traverser} into another. This class
simply requires the implementation of the {@link #map(Traverser.Admin)} method to extract the object of the given
{@link Traverser} and return the transformation of that object as {@code E}.

@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/ScalarMapStep.java