MutableGraph<Integer> g1 = builder.build();
    MutableGraph<Integer> g2 = builder.build();

    // for g1, add 1->2 first, then 3->1
    g1.putEdge(N1, N2);
    g1.putEdge(N3, N1);

    // for g2, add 3->1 first, then 1->2
    g2.putEdge(N3, N1);
    g2.putEdge(N1, N2);

    assertThat(g1).isEqualTo(g2);
  }

  @Test

    MutableNetwork<Integer, String> g1 = builder.build();
    MutableNetwork<Integer, String> g2 = builder.build();

    // for ug1, add e12 first, then e12_a
    g1.addEdge(N1, N2, E12);
    g1.addEdge(N1, N2, E12_A);

    // for ug2, add e12_a first, then e12
    g2.addEdge(N1, N2, E12_A);
    g2.addEdge(N1, N2, E12);

    assertThat(g1).isEqualTo(g2);
  }

  @Test

    MutableNetwork<Integer, String> g1 = builder.build();
    MutableNetwork<Integer, String> g2 = builder.build();

    // for ug1, add e12 first, then e12_a
    g1.addEdge(N1, N2, E12);
    g1.addEdge(N1, N2, E12_A);

    // for ug2, add e12_a first, then e12
    g2.addEdge(N1, N2, E12_A);
    g2.addEdge(N1, N2, E12);

    assertThat(g1).isEqualTo(g2);
  }

  @Test