abstract Network<N, E> delegate();

  @Override
  public Set<N> nodes() {
    return delegate().nodes();
  }

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

  @Override
  public boolean isDirected() {
    return delegate().isDirected();
  }

  @Override
  public boolean allowsParallelEdges() {

)

type backedgesState struct {
	b *Block
	i int
}

// backedges returns a slice of successor edges that are back
// edges.  For reducible loops, edge.b is the header.
func backedges(f *Func) []Edge {
	edges := []Edge{}
	mark := make([]markKind, f.NumBlocks())
	stack := []backedgesState{}

	mark[f.Entry.ID] = notExplored

		}
	}

	edges := EdgeMap{}

	// Add nodes and nodelets to DOT builder.
	for _, n := range g.Nodes {
		builder.addNode(n, nodeIDMap[n], maxFlat)
		hasNodelets[n] = builder.addNodelets(n, nodeIDMap[n])

		// Collect all edges. Use a fake node to support multiple incoming edges.
		for _, e := range n.Out {
			edges[&Node{}] = e
		}
	}

  static final String MULTIPLE_EDGES_CONNECTING =
      "Cannot call edgeConnecting() when parallel edges exist between %s and %s. Consider calling "
          + "edgesConnecting() instead.";
  static final String PARALLEL_EDGES_NOT_ALLOWED =
      "Nodes %s and %s are already connected by a different edge. To construct a graph "
          + "that allows parallel edges, call allowsParallelEdges(true) on the Builder.";
  static final String SELF_LOOPS_NOT_ALLOWED =

        // the following only needs to be done serially to preserve ordering of dependencies in the graph: we have visited the edges
        // but we still didn't add the result to the queue. Doing it from resolve threads would result in non-reproducible graphs, where
        // edges could be added in different order. To avoid this, the addition of new edges is done serially.
        for (EdgeState dependency : dependencies) {

}

Status Encapsulator::AddEdgesToOutputGraph(
    const absl::flat_hash_map<const Node*, Node*>& node_images,
    Graph* graph_out) {
  // Set of edges already added to the output graph, represented as (src, dst)
  // pairs. We use the set to deduplicate edges; multiple edges in the input
  // graph may map to one edge in the output graph.
  absl::flat_hash_set<std::pair<OutputTensor, InputTensor>,

          assertThat(graph.hasEdgeConnecting(endpoints.nodeU(), endpoints.nodeV())).isTrue();
        }
      }
    }

    sanityCheckSet(graph.edges());
    assertThat(graph.edges()).doesNotContain(EndpointPair.of(graph, new Object(), new Object()));
    assertThat(graph.edges()).isEqualTo(allEndpointPairs);
  }

  /**
   * Verifies that the {@code Set} returned by {@code nodes} has the expected mutability property

  abstract Network<N, E> delegate();

  @Override
  public Set<N> nodes() {
    return delegate().nodes();
  }

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

  @Override
  public boolean isDirected() {
    return delegate().isDirected();
  }

  @Override
  public boolean allowsParallelEdges() {

  static final String MULTIPLE_EDGES_CONNECTING =
      "Cannot call edgeConnecting() when parallel edges exist between %s and %s. Consider calling "
          + "edgesConnecting() instead.";
  static final String PARALLEL_EDGES_NOT_ALLOWED =
      "Nodes %s and %s are already connected by a different edge. To construct a graph "
          + "that allows parallel edges, call allowsParallelEdges(true) on the Builder.";
  static final String SELF_LOOPS_NOT_ALLOWED =

  graph_->AddEdge(input_node_it->second, 0, dst_node, dst_index);
  return absl::OkStatus();
}

Status Exporter::AddEdge(Operation* inst) {
  // For tf_executor.fetch, add only its data edges. Control edges are captured
  // later.
  if (auto fetch = llvm::dyn_cast<mlir::tf_executor::FetchOp>(inst)) {
    for (auto operand_and_idx : llvm::enumerate(fetch.getOperands())) {
      Value operand = operand_and_idx.value();