code: def test_insertfilter(self):
      self.assertIsNotNone(self.filter_one.delegate)
      self.assertEqual(self.percolator.top, self.filter_two)
      self.assertEqual(self.filter_two.delegate, self.filter_one)
      self.assertEqual(self.filter_one.delegate, self.percolator.bottom)
  
imports: from idlelib.percolator import Percolator, Delegator
  import unittest
  from test.support import requires
  from tkinter import Text, Tk, END
label_desc: Use image node_id 5 for calling the PercolatorTest obj's underlying member method code with example usage: obj.test_insertfilter() without return types