@Override
    protected List<Traversal> getTraversals() {
        return Arrays.asList(
                __.sack(Operator.mult).by("weight"),
                __.sack(Operator.max).by("weight"),
                __.sack(Operator.max).by("age"),
                __.sack((Map m, Vertex v) -> {
                    m.put(v.value("name"), v.value("lang"));
                    return m;
                }),
                __.sack((Map m, Vertex v) -> {
                    m.put(v.value("lang"), v.value("name"));
                    return m;
                })
        );
    }
@author Daniel Kuppitz (http://gremlin.guru)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/process/traversal/step/sideEffect/SackValueStepTest.java