message: Clarify documentation of Dataset.filter
  It was not explicitly stated that the predicate should return True for elements the user wants to keep.
diff: @@ -967,7 +967,8 @@ class Dataset(object):
  scalar `tf.bool` tensor.
  Returns:
  - Dataset: A `Dataset`.
  + Dataset: The `Dataset` containing the elements of this dataset for which
  + `predicate` is `True`.
  """
  return FilterDataset(self, predicate)
  