code: def __getitem__(self, session_id: str) -> SessionState:
      if session_id not in self.session_data:
          self.session_data[session_id] = SessionState(self.blocks)
      self.update(session_id)
      return self.session_data[session_id]
  
file_path: gradio/gradio/state_holder.py
imports: from __future__ import annotations
  import threading
  from collections import OrderedDict
  from copy import deepcopy
  from typing import TYPE_CHECKING, Any
label_desc: Use image node_id 3 for calling the StateHolder obj's underlying member method code with example usage: obj.__getitem__(session_id) and returns: self