old_contents: # -*- coding: utf-8 -*-
  """
  module_0.py
  
  Introduction to modules
  =======================
  
  This module serves as an example for how everything should
  look in a typical module. You can copy this module and use it as a template.
  
  To run the tests, open a command prompt in the root directory (the one that
  contains setup.py: 'learn_python') and type `python setup.py tests`
  This will find and run all of the tests in this project.
  
  To only run the tests for this module (this is not the typical way of doing
  things, but it might be more convenient under these circumstances), simply
  run this module and the script at the bottom will automatically run the tests
  for this module.
  
  Alternatively, you can run the tests for this module directly from the command
  line:
      `python -m unittest tests/test_module_0.py
  """
  
  
  def hello_world():
      """
      Print 'Hello World' to the screen.
  
      Args:
      ----
          none
  
      Returns:
      -------
          True
      """
      print("Hello World!")
      return True
  
  if __name__ == '__main__':
  
      import unittest
  
      testsuite = unittest.TestLoader().discover('.')
      unittest.TextTestRunner(verbosity=2).run(testsuite)
  
new_contents: # -*- coding: utf-8 -*-
  """
  module_0.py
  
  Introduction to modules
  =======================
  
  This module serves as an example for how everything should
  look in a typical module. You can copy this module and use it as a template.
  
  To run the tests, open a command prompt in the root directory (the one that
  contains setup.py: 'learn_python') and type `python setup.py tests`
  This will find and run all of the tests in this project.
  
  To only run the tests for this module (this is not the typical way of doing
  things, but it might be more convenient under these circumstances), simply
  run this module and the script at the bottom will automatically run the tests
  for this module.
  
  Alternatively, you can run the tests for this module directly from the command
  line:
      `python -m unittest tests/test_module_0.py
  """
  
  
  def hello_world():
      """
      Print 'Hello World' to the screen.
  
      Args:
      ----
          none
  
      Returns:
      -------
          True
      """
      print("Hello World!")
      return True
  
  
  if __name__ == '__main__':
  
      print('Inside of module_0.main()')
      import unittest
  
      # run the test module that corresponds to this module.
      unittest.main("tests.test_module_0", verbosity=2)
  
subject: add a testing function to module_0