message: Remove unneeded lines.
  There's no need to keep a separate set to track the seen nodes (`visited_nodes` because `path` is already effectively filtering out the duplicate nodes)
diff: @@ -204,13 +204,9 @@ def _generate_object_paths(object_graph_def):
  """Traverses through an ObjectGraphDef and builds a map of all node paths."""
  paths = {0: 'root'}
  nodes_to_visit = [0]
  - visited_nodes = set([])
  while nodes_to_visit:
  current_node = nodes_to_visit.pop()
  - # if current_node in visited_nodes:
  - # continue
  - visited_nodes.add(current_node)
  current_path = paths[current_node]
  for reference in object_graph_def.nodes[current_node].children:
  if reference.node_id in paths:
  