class_docstr: (contextlib.nested is not available on Py3)
code: def __exit__(self, *a: object) -> None:
      pass
  
imports: from __future__ import annotations
  import os
  import signal
  import sys
  import threading
  from collections import deque
  from typing import Callable, ContextManager, Dict, Generator, Generic, TypeVar, Union
  from wcwidth import wcwidth
label_desc: Use image node_id 2 for calling the DummyContext obj's underlying member method code with example usage: obj.__exit__() without return types