code: def pairwise(
      iterable: Iterable,
      default_value: Any,
  ) -> Iterable[Tuple[Any, Any]]:
      
      a, b = tee(iterable)
      _ = next(b, default_value)
      return zip_longest(a, b, fillvalue=default_value)
docs: Return pairs of items from `iterable`.
  
      pairwise([1, 2, 3], default_value=None) -> (1, 2) (2, 3), (3, None)