@Override
    public Set<MessageScope> getMessageScopes(final Memory memory) {
        final Set<MessageScope> set = new HashSet<>();
        set.add(memory.isInitialIteration() ? this.countMessageScope : this.incidentMessageScope);
        return set;
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/ranking/pagerank/PageRankVertexProgram.java