new_contents: """
  Program to join a list of strings with a given separator
  """
  
  
  def join(separator: str, separated: list) -> str:
      """
      >>> join("", ["a", "b", "c", "d"])
      'abcd'
      >>> join("#", ["a", "b", "c", "d"])
      'a#b#c#d'
      >>> join("#", "a")
      'a'
      >>> join(" ", ["You", "are", "amazing!"])
      'You are amazing!'
      >>> join("#", ["a", "b", "c", 1])
      Traceback (most recent call last):
      ...
      Exception: join() accepts only strings to be joined
      """
      joined = ""
      for word_or_phrase in separated:
          if not isinstance(word_or_phrase, str):
              raise Exception("join() accepts only strings to be joined")
          joined += word_or_phrase + separator
      return joined.strip(separator)
  
  
  if "__name__" == "__main__":
      from doctest import testmod
  
      testmod()
  
subject: Create join.py (#5363)