@Override
    public void set(final String key, final Object value) {
        checkKeyValue(key, value);
        if (this.inExecute)
            throw Memory.Exceptions.memorySetOnlyDuringVertexProgramSetUpAndTerminate(key);
        this.currentMap.put(key, Optional.ofNullable(value));
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
tinkergraph-gremlin/src/main/java/org/apache/tinkerpop/gremlin/tinkergraph/process/computer/TinkerMemory.java