@Override
        public Edge addEdge(final String label, final Vertex inVertex, final Object... keyValues) {
            if (state.equals(State.MAP_REDUCE))
                throw GraphComputer.Exceptions.incidentAndAdjacentElementsCanNotBeAccessedInMapReduce();
            return new ComputerEdge(this.getBaseVertex().addEdge(label, inVertex, keyValues));
        }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/util/ComputerGraph.java