docs: def format_expose(expose):
      """
      Converts a port number or multiple port numbers, as used in the Dockerfile ``EXPOSE`` command, to a tuple.
  
      :param: Port numbers, can be as integer, string, or a list/tuple of those.
      :type expose: int | unicode | str | list | tuple
      :return: A tuple, to be separated by spaces before inserting in a Dockerfile.
      :rtype: tuple
      """
      if isinstance(expose, six.string_types):
          return expose,
      elif isinstance(expose, collections.Iterable):
          return map(six.text_type, expose)
      return six.text_type(expose),