code: def post_order_traverse(root, all_ops, post_order_results):
      """
      Traversal a tree in post order.
      Args:
          root: current node of the tree.
          all_ops: used to index all nodes.
          post_order_results(list): used to store traversal results in place.
      """
      for child in all_ops[root]["children_node"]:
          post_order_traverse(child, all_ops, post_order_results)
      post_order_results.append(root)
      return
  
file_path: VisualDL/visualdl/component/graph/graph_component.py
imports: import collections
  import os.path
  import pathlib
  import re
  from .None import utils
label_desc: Use image node_id 1 for calling a global function with example usage: post_order_traverse(root, all_ops, post_order_results) without return types