code: def _extra_config_file_changed(self, change):
      old = change["old"]
      new = change["new"]
      try:
          self.config_files.remove(old)
      except ValueError:
          pass
      self.config_file_specified.add(new)
      self.config_files.append(new)
  
imports: import atexit
  from copy import deepcopy
  import glob
  import logging
  import os
  import shutil
  import sys
  from traitlets.config.application import Application, catch_config_error
  from traitlets.config.loader import ConfigFileNotFound, PyFileConfigLoader
  from IPython.core import release, crashhandler
  from IPython.core.profiledir import ProfileDir, ProfileDirError
  from IPython.paths import get_ipython_dir, get_ipython_package_dir
  from IPython.utils.path import ensure_dir_exists
  from IPython.utils import py3compat
  from traitlets import List, Unicode, Type, Bool, Dict, Set, Instance, Undefined, default, observe
label_desc: Use image node_id 4 for calling the BaseIPythonApplication obj's underlying member method code with example usage: obj._extra_config_file_changed(change) without return types