message: const removed
diff: @@ -168,7 +168,7 @@ std::vector<bool> SymbolicGradientBuilder::GetReachableNodes() {
  std::vector<bool> reachable_nodes(scope_.graph()->num_node_ids(), false);
  std::deque<Node*> queue;
  for (const Output& out : outputs_) {
  - const Node* const out_node = out.node();
  + Node* const out_node = out.node();
  const int out_node_id = out_node->id();
  if (!reachable_nodes[out_node_id]) {
  queue.push_back(out_node);
  @@ -181,7 +181,7 @@ std::vector<bool> SymbolicGradientBuilder::GetReachableNodes() {
  queue.pop_front();
  for (const Edge* e : n->in_edges()) {
  if (e->IsControlEdge()) continue;
  - const Node* const src_node = e->src();
  + Node* const src_node = e->src();
  const int src_node_id = src_node->id();
  if (!reachable_nodes[src_node_id]) {
  queue.push_back(src_node);
  