protected boolean isEndStep() {
        return this.getNextStep() instanceof ComputerResultStep || (this.getNextStep() instanceof ProfileStep && this.getNextStep().getNextStep() instanceof ComputerResultStep);
    }
@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