for (Range<Integer> rangeToPut : RANGES) {
      for (Range<Integer> rangeToRemove : RANGES) {
        Map<Integer, Integer> model = new HashMap<>();
        putModel(model, rangeToPut, 1);
        removeModel(model, rangeToRemove);
        RangeMap<Integer, Integer> test = TreeRangeMap.create();
        test.put(rangeToPut, 1);
        test.remove(rangeToRemove);
        verify(model, test);
      }
    }
  }

  @Test
  public void removeNode_existingNode() {
    assume().that(graphIsMutable()).isTrue();

    putEdge(N1, N2);
    putEdge(N4, N1);
    assertThat(graphAsMutableGraph.removeNode(N1)).isTrue();
    assertThat(graphAsMutableGraph.removeNode(N1)).isFalse();
    assertThat(graph.nodes()).containsExactly(N2, N4);

    assertThat(graph.adjacentNodes(N2)).isEmpty();
    assertThat(graph.predecessors(N2)).isEmpty();

  @Test
  public void removeNode_existingNode() {
    assume().that(graphIsMutable()).isTrue();

    putEdge(N1, N2);
    putEdge(N4, N1);
    assertThat(graphAsMutableGraph.removeNode(N1)).isTrue();
    assertThat(graphAsMutableGraph.removeNode(N1)).isFalse();
    assertThat(graph.nodes()).containsExactly(N2, N4);

    assertThat(graph.adjacentNodes(N2)).isEmpty();
    assertThat(graph.predecessors(N2)).isEmpty();

        if (root == null) {
            return false;
        }

        Element modelVersionElement = root.child(MODEL_VERSION).orElse(null);
        if (modelVersionElement != null) {
            return root.removeNode(modelVersionElement);
        }
        return false;
    }

    /**
     * Gets the schema location for a model version.
     *
     * @param modelVersion the model version

    assume().that(graphIsMutable()).isTrue();
    assume().that(network.allowsSelfLoops()).isTrue();

    addNode(N1);
    addEdge(N1, N1, E11);
    assertThat(networkAsMutableNetwork.removeNode(N1)).isTrue();
    assertThat(network.nodes()).isEmpty();
    assertThat(network.edges()).doesNotContain(E11);
  }

  @Test
  public void removeEdge_existingSelfLoopEdge() {