code: def undo_block_start(self):
      pass
  
imports: import unittest
  from idlelib import FormatParagraph
  from idlelib.EditorWindow import EditorWindow
  from Tkinter import Tk, Text
  from test.test_support import requires
label_desc: Use image node_id 3 for calling the TextWrapper obj's underlying member method code with example usage: obj.undo_block_start() without return types