code: def get_node(self, tag: str, key: str):
      if tag == "iso":
          return self.iso2node[key]
      # elif tag == "name":
      #     return self.name2node[key]
      else:
          raise NotImplementedError(
              f'Searching not supported. Support tags: "iso", "name".'
          )
  
imports: import json
  from typing import Dict, List, Union
label_desc: Use image node_id 5 for calling the LanguageTree obj's underlying member method code with example usage: obj.get_node(tag, key) and returns: self