code: public static void saveGraph(DirectedGraph<Integer, DefaultEdge> graph, File file) throws IOException {
  		SerializableDirectedGraph serialGraph = new SerializableDirectedGraph(graph);
  		BufferedOutputStream fos;
  		ObjectOutputStream out;
  		fos = new BufferedOutputStream(new FileOutputStream(file));
  		out = new ObjectOutputStream(fos);
  		out.writeObject(serialGraph);
  		out.close();
  
  	}
docs: Serializes the given {@link DirectedGraph} object to the given location.
  
  @param graph Must not be {@code null}.
  @param file Must not be {@code null} and valid {@link File}.
  @throws IOException Thrown if errors occurred on the IO level.