private void processMemorySideEffects(final Memory memory) {
        // update the traversal side-effects with the state of the memory after the OLAP job execution
        final TraversalSideEffects sideEffects = this.getTraversal().getSideEffects();
        for (final String key : memory.keys()) {
            if (sideEffects.exists(key)) {
                // halted traversers should never be propagated through sideEffects
                assert !key.equals(TraversalVertexProgram.HALTED_TRAVERSERS);
                sideEffects.set(key, memory.get(key));
            }
        }
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/traversal/step/map/VertexProgramStep.java