class_docstr: Abstract class representing tree items.
  
  Methods should typically be overridden, otherwise a default action
  is used.
class_docstr_tok: ["Abstract","class","representing","tree","items",".","Methods","should","typically","be","overridden",",","otherwise","a","default","action","is","used","."]
docstr: Do not override!  Called by TreeNode.
docstr_tok: ["Do","not","override","!","Called","by","TreeNode","."]
code: def _IsExpandable(self):
      """Do not override!  Called by TreeNode."""
      if self.expandable is None:
          self.expandable = self.IsExpandable()
      return self.expandable
  
imports: import os
  from tkinter import *
  from tkinter.ttk import Frame, Scrollbar
  from idlelib.config import idleConf
  from idlelib import zoomheight
label_desc: Use image node_id 4 for calling the TreeItem obj's underlying member method code with example usage: obj._IsExpandable() and returns: self