old_contents: # This program also handles an error
  def spam(divideBy):
      return 42 / divideBy
  
  
  try:
      print(spam(2))
      print(spam(12))
      print(spam(0))
      print(spam(1))  # skipped due to error
  except ZeroDivisionError:
      print('Error: Invalid argument.')
  
new_contents: """Zero divide 3.0
  
  This program also handles a :class:`ZeroDivisionError`, but in the :meth:`~main` function.
  
  """
  
  
  def spam(divideBy: int) -> float:
      """Spam
  
      Divides integer 42 by given integer.
  
      Args:
          divideBy: Integer to divide 42 by.
  
      Returns:
          Float result of 42 divided by given integer.
      """
      return 42 / divideBy
  
  
  def main():
      try:
          print(spam(2))
          print(spam(12))
          print(spam(0))
          print(spam(1))  # skipped due to error
      except ZeroDivisionError:
          print('Error: Invalid argument.')
  
  
  if __name__ == '__main__':
      main()
  
subject: Update P10_zeroDivide3.py added docstrings and wrapped in main() function