static final String ERROR_ADDED_SELF_LOOP = "Should not be allowed to add a self-loop edge.";
  static final String ERROR_ADDED_PARALLEL_EDGE = "Should not be allowed to add a parallel edge.";
  static final String ERROR_ADDED_EXISTING_EDGE =
      "Reusing an existing edge to connect different nodes succeeded";

  /** Creates and returns an instance of the graph to be tested. */

  static final String ERROR_ADDED_SELF_LOOP = "Should not be allowed to add a self-loop edge.";
  static final String ERROR_ADDED_PARALLEL_EDGE = "Should not be allowed to add a parallel edge.";
  static final String ERROR_ADDED_EXISTING_EDGE =
      "Reusing an existing edge to connect different nodes succeeded";

  /** Creates and returns an instance of the graph to be tested. */

  /**
   * Returns the nodes which are the endpoints of {@code edge} in this network.
   *
   * @throws IllegalArgumentException if {@code edge} is not an element of this network
   */
  EndpointPair<N> incidentNodes(E edge);

  /**
   * Returns a live view of the edges which have an {@link #incidentNodes(Object) incident node} in
   * common with {@code edge}. An edge is not considered adjacent to itself.
   *

            () -> networkAsMutableNetwork.addEdge(N1, N2, EDGE_NOT_IN_GRAPH));
    assertThat(e).hasMessageThat().contains(ERROR_PARALLEL_EDGE);
    e =
        assertThrows(
            IllegalArgumentException.class,
            () -> networkAsMutableNetwork.addEdge(N2, N1, EDGE_NOT_IN_GRAPH));
    assertThat(e).hasMessageThat().contains(ERROR_PARALLEL_EDGE);
  }

  @Test

                "wrong edge v1-v2 in the resulting graph after resolver");

        assertEquals(
                1, res.getIncidentEdges(v3).size(), "wrong # of edges v1-v3 in the resulting graph after resolver");
        assertEquals(
                "1.1",
                res.getIncidentEdges(v3).get(0).getVersion(),
                "wrong edge v1-v3 in the resulting graph after resolver");

  static final String ERROR_ELEMENT_REMOVED = "used to generate this set";
  private static final String NODE_STRING = "Node";
  private static final String EDGE_STRING = "Edge";

  enum EdgeType {
    UNDIRECTED,
    DIRECTED;
  }

  private TestUtil() {}

  static void assertNodeNotInGraphErrorMessage(Throwable throwable) {

  static final String ERROR_ELEMENT_REMOVED = "used to generate this set";
  private static final String NODE_STRING = "Node";
  private static final String EDGE_STRING = "Edge";

  enum EdgeType {
    UNDIRECTED,
    DIRECTED;
  }

  private TestUtil() {}

  static void assertNodeNotInGraphErrorMessage(Throwable throwable) {

    }
    return connections;
  }

  final N checkedReferenceNode(E edge) {
    N referenceNode = edgeToReferenceNode.get(edge);
    if (referenceNode == null) {
      checkNotNull(edge);
      throw new IllegalArgumentException(String.format(EDGE_NOT_IN_GRAPH, edge));
    }
    return referenceNode;
  }

  final boolean containsNode(N node) {

    while discussion_edges:
        for discussion_edge in discussion_edges:
            discussion_nodes.append(discussion_edge.node)
        last_edge = discussion_edges[-1]
        discussion_edges = get_graphql_question_discussion_edges(
            settings=settings, after=last_edge.cursor
        )
    return discussion_nodes


def get_discussions_experts(

  static final String EDGE_ALREADY_EXISTS = "Edge %s already exists in the graph.";
  static final String ENDPOINTS_MISMATCH =
      "Mismatch: endpoints' ordering is not compatible with directionality of the graph";

  /** Singleton edge value for {@link Graph} implementations backed by {@link ValueGraph}s. */
  enum Presence {
    EDGE_EXISTS
  }