List<Integer> sources = Arrays.asList(1, 2, 3, 4, 5);
List<Integer> targets = Arrays.asList(5, 4, 3, 2, 1);
List<String> edata = Arrays.asList("a", "b", "c", "d", "e");
assertEquals(mygraph.numEdges(), 0);
mygraph.addEdges(sources, targets, edata);
assertEquals(mygraph.numEdges(), sources.size());
SimpleJsonFormatter formatter = new SimpleJsonFormatter();
String s = formatter.structWriter(mygraph).toString();
String expected = "{\"source\":1,\"targets\":[5]}\n"