code: def client_id_from_id_token(id_token):
      
      payload = JWT().unpack(id_token).payload()
      aud = payload.get('aud', None)
      if aud is None:
          return None
      if isinstance(aud, list):
          return aud[0]
      return aud
docs: Extracts the client id from a JSON Web Token (JWT).
      Returns a string or None.