class_docstr: Sidebar for the PyShell window, for prompts etc.
code: def change_callback(self):
      if self.is_shown:
          self.update_sidebar()
  
imports: import contextlib
  import functools
  import itertools
  import tkinter
  from tkinter.font import Font
  from idlelib.config import idleConf
  from idlelib.delegator import Delegator
  from idlelib import macosx
label_desc: Use image node_id 6 for calling the ShellSidebar obj's underlying member method code with example usage: obj.change_callback() without return types