code: def unpack_default(iterable, length=3, default=None):
      
  
      return itertools.islice(itertools.chain(iter(iterable), itertools.repeat(default)), length)
docs: Unpacks given iterable maintaining given length and filling missing entries with given default.
  
      :param iterable: iterable.
      :type iterable: object
      :param length: Iterable length.
      :type length: int
      :param default: Filling default object.
      :type default: object
      :return: Unpacked iterable.
      :rtype: object