old_contents: from django.test import TestCase
  
  from .. import utils
  
  
  class TestDisplayFeedback(TestCase):
  
      def test_false(self):
          bad_feedback = [None, '', '    ', ' 1', '1', 'yes', 'Yes', 'YES',
                          'no', 'No', 'NO', '55999']
          for bad in bad_feedback:
              self.assertEqual(utils.display_feedback(bad), False)
  
      def test_true(self):
          good_feedback = ['Yes this is good', 'Great feedback']
          for good in good_feedback:
              self.assertEqual(utils.display_feedback(good), True)
  
new_contents: from django.test import TestCase
  
  from .. import utils
  
  
  class TestDisplayFeedback(TestCase):
  
      def test_false(self):
          bad_feedback = [None, '', '    ', ' 1', '1', 'yes', 'Yes', 'YES',
                          'no', 'No', 'NO', '55999', 'n0']
          for bad in bad_feedback:
              self.assertEqual(utils.display_feedback(bad), False)
  
      def test_true(self):
          good_feedback = ['Yes this is good', 'Great feedback', '20']
          for good in good_feedback:
              self.assertEqual(utils.display_feedback(good), True)
  
subject: add tests for hiding "n0" and showing two-digit numbers