old_contents: import unittest
  
  
  class MarkedTests(unittest.TestCase):
      pass
  
  
  if __name__ == '__main__':
      unittest.main()
  
new_contents: import unittest
  
  import marked
  
  
  class MarkedTests(unittest.TestCase):
      pass
  
  
  if __name__ == '__main__':
      unittest.main()
  
subject: Add import for marked to tests