MutableNetwork<String, Integer> network = NetworkBuilder.directed().build();
    network.addEdge("a", "b", 11);

    Traverser.forTree(network); // Does not throw
  }

  @Test
  public void forTree_withUndirectedNetwork_throws() throws Exception {
    MutableNetwork<String, Integer> network = NetworkBuilder.undirected().build();
    network.addEdge("a", "b", 11);

      *node_def->mutable_op() = "Stateless" + node_def->op();
  }

  // Add inputs to the NodeDef based on the number of operands. This is required
  // as later when edges are added to the Node using Graph::AddEdge the
  // associated NodeDef is not updated.
  for (int i = 0, e = inst->getNumOperands(); i < e; ++i) {
    node_def->add_input();
  }
  if (auto attr = inst->getAttrOfType<mlir::StringAttr>("device")) {