public Builder distanceTraversal(final Traversal<Edge, Number> distanceTraversal) {
            if (null == distanceTraversal) throw Graph.Exceptions.argumentCanNotBeNull("distanceTraversal");
            PureTraversal.storeState(this.configuration, DISTANCE_TRAVERSAL, distanceTraversal.asAdmin());
            return this;
        }
Move any valid path into the VP's memory.
@param vertex The current vertex.
@param memory The VertexProgram's memory.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/search/path/ShortestPathVertexProgram.java