old_contents: from threading import Thread
  global exit_flag
  exit_flag = False
  def g():
      i = 1
      while not exit_flag:
          i = (i + 1) % 100000000
          if i % 100000 == 0: print("f making progress: {0}".format(i))
  
  def f():
      g()
  
  from threading import Thread
  
  def n():
      t1 = Thread(target=f,name="F_thread")
      t1.start()
      t1.join()
  
  def m():
      n()
  
  if __name__ == '__main__':
      m()
  
new_contents: from threading import Thread
  global exit_flag
  exit_flag = False
  def g():
      i = 1
      while not exit_flag:
          i = (i + 1) % 100000000
          if i % 100000 == 0: print("f making progress: {0}".format(i))
  
  def f():
      g()
  
  def n():
      t1 = Thread(target=f,name="F_thread")
      t1.start()
      t1.join()
  
  def m():
      n()
  
  if __name__ == '__main__':
      m()
  
subject: Remove redundant import from test script.