assertThat(network.removeNode(nodeList.get(i))).isTrue();
      }

      assertThat(network.nodes()).hasSize(NUM_NODES - numNodesToRemove);
      // Number of edges remaining is unknown (node's incident edges have been removed).
      AbstractNetworkTest.validateNetwork(network);

      for (int i = numNodesToRemove; i < NUM_NODES; ++i) {
        assertThat(network.removeNode(nodeList.get(i))).isTrue();
      }

 * graphs. Instances of this class should be constructed with {@link NetworkBuilder}.
 *
 * <p>Time complexities for mutation methods are all O(1) except for {@code removeNode(N node)},
 * which is in O(d_node) where d_node is the degree of {@code node}.
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @author Omar Darwish
 * @param <N> Node parameter type

   *
   * @return {@code true} if the network was modified as a result of this call
   */
  @CanIgnoreReturnValue
  boolean removeNode(N node);

  /**
   * Removes {@code edge} from this network, if it is present.
   *
   * @return {@code true} if the network was modified as a result of this call
   */
  @CanIgnoreReturnValue

        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

   *
   * @return {@code true} if the network was modified as a result of this call
   */
  @CanIgnoreReturnValue
  boolean removeNode(N node);

  /**
   * Removes {@code edge} from this network, if it is present.
   *
   * @return {@code true} if the network was modified as a result of this call
   */
  @CanIgnoreReturnValue