code: def add_child(self, node):
      self.children[node.name] = node
      if isinstance(node, InternalNode):
          self.num += node.num
      else:
          self.num += 1
  
imports: import json
  from typing import Dict, List, Union
label_desc: Use image node_id 2 for calling the InternalNode obj's underlying member method code with example usage: obj.add_child(node) without return types