code: def __getitem__(self, key: Any) -> "KeysRecorder":
      """Wrap method `__getitem__`  to record its keys.
  
      Args:
          key: Key that is passed to the object.
  
      Returns:
          result (KeysRecorder): KeysRecorder instance that wraps sub_obj.
      """
      sub_obj = self.obj.__getitem__(key)
      keys = self.keys.copy()
      keys.append(key)
      # Create a KeysRecorder instance from the sub_obj.
      result = KeysRecorder(sub_obj, keys)
      return result
  
imports: from typing import Any, List, Optional
label_desc: Use image node_id 2 for calling the KeysRecorder obj's underlying member method code with example usage: obj.__getitem__(key) and returns: result