code: def test_comment_region_event(self):
      comment = self.formatter.comment_region_event
      text = self.text
      eq = self.assertEqual
  
      text.tag_add("sel", "7.0", "10.0")
      comment()
      eq(
          text.get("7.0", "10.0"),
          ("##\n##    def compare(self):\n##        if a > b:\n"),
      )
  
imports: from idlelib import format
  import unittest
  from unittest import mock
  from test.support import requires
  from tkinter import Tk, Text
  from idlelib.editor import EditorWindow
  from idlelib.idle_test.mock_idle import Editor
label_desc: Use image node_id 9 for calling the FormatRegionTest obj's underlying member method code with example usage: obj.test_comment_region_event() without return types