@Override
  public Set<E> adjacentEdges(E edge) {
    EndpointPair<N> endpointPair = incidentNodes(edge); // Verifies that edge is in this network.
    Set<E> endpointPairIncidentEdges =
        Sets.union(incidentEdges(endpointPair.nodeU()), incidentEdges(endpointPair.nodeV()));
    return edgeInvalidatableSet(
        Sets.difference(endpointPairIncidentEdges, ImmutableSet.of(edge)), edge);
  }

  @Override

  }

  @Override
  public EndpointPair<N> incidentNodes(E edge) {
    N nodeU = checkedReferenceNode(edge);
    // requireNonNull is safe because checkedReferenceNode made sure the edge is in the network.
    N nodeV = requireNonNull(nodeConnections.get(nodeU)).adjacentNode(edge);
    return EndpointPair.of(this, nodeU, nodeV);
  }

  @Override

  }

  @Override
  public EndpointPair<N> incidentNodes(E edge) {
    N nodeU = checkedReferenceNode(edge);
    // requireNonNull is safe because checkedReferenceNode made sure the edge is in the network.
    N nodeV = requireNonNull(nodeConnections.get(nodeU)).adjacentNode(edge);
    return EndpointPair.of(this, nodeU, nodeV);
  }

  @Override

        while (resultWithDoubleSelfLoop.hasNext()) {
          EndpointPair<N> edge = resultWithDoubleSelfLoop.next();
          if (edge.nodeU().equals(edge.nodeV())) {
            if (!alreadySeenSelfLoop.getAndSet(true)) {
              return edge;
            }
          } else {
            return edge;
          }
        }
        return endOfData();
      }
    };
  }

      mutableValueGraph.addNode(node);
      return this;
    }

    /**
     * Adds an edge connecting {@code nodeU} to {@code nodeV} if one is not already present, and
     * sets a value for that edge to {@code value} (overwriting the existing value, if any).
     *
     * <p>If the graph is directed, the resultant edge will be directed; otherwise, it will be
     * undirected.
     *

            List<String> cycle = visitCycle(graph, Collections.singleton(to), new HashMap<>(), new LinkedList<>());
            if (cycle != null) {
                // remove edge which introduced cycle
                throw new CycleDetectedException(
                        "Edge between '" + from + "' and '" + to + "' introduces to cycle in the graph", cycle);
            }
        }
    }

    private enum DfsState {
        VISITING,

    assertThat(network.edgeOrder())
        .isEqualTo(ElementOrder.sorted(Ordering.<String>natural().reverse()));
    assertThat(network.edges()).containsExactly("p", "i", "e").inOrder();
    assertThat(network.nodeOrder()).isEqualTo(ElementOrder.insertion()); // default
  }

  // Combined node and edge order tests

  @Test
  public void nodeOrderUnorderedAndEdgesSorted() {
    MutableNetwork<Integer, String> network =

  public Set<E> outEdges(N node) {
    return delegate().outEdges(node);
  }

  @Override
  public EndpointPair<N> incidentNodes(E edge) {
    return delegate().incidentNodes(edge);
  }

  @Override
  public Set<E> adjacentEdges(E edge) {
    return delegate().adjacentEdges(edge);
  }

  @Override
  public int degree(N node) {
    return delegate().degree(node);
  }

  @Override

import org.jspecify.annotations.Nullable;

/**
 * A class to represent the set of edges connecting an (implicit) origin node to a target node.
 *
 * <p>The {@link #nodeToOutEdge} map means this class only works on networks without parallel edges.
 * See {@link MultiEdgesConnecting} for a class that works with parallel edges.
 *
 * @author James Sexton
 * @param <E> Edge parameter type
 */
final class EdgesConnecting<E> extends AbstractSet<E> {

    public Builder<N> addNode(N node) {
      mutableGraph.addNode(node);
      return this;
    }

    /**
     * Adds an edge connecting {@code nodeU} to {@code nodeV} if one is not already present.
     *
     * <p>If the graph is directed, the resultant edge will be directed; otherwise, it will be
     * undirected.
     *