message: fix group_by_window api call for backward-compatibility
diff: @@ -119,8 +119,12 @@ def group_by_window(key_func,
  def _apply_fn(dataset):
  """Function from `Dataset` to `Dataset` that applies the transformation."""
  - return dataset.group_by_window(dataset, key_func, reduce_func,
  - window_size_func)
  + return dataset.group_by_window(
  + key_func=key_func,
  + reduce_func=reduce_func,
  + window_size=window_size,
  + window_size_func=window_size_func
  + )
  return _apply_fn
  