));          Set<Integer> verts = new HashSet<Integer>();         for (int i = 0; i < 0; ++i)             verts.add(i);          DirectedMultigraph<String> sub = g.subgraph(verts);         assertEquals(0, sub.order());         assertEquals(0, sub.size());               Set<DirectedTypedEdge<String>> edges = sub.edges();         assertEquals(0, edges.size());         