def METHOD_NAME(  # pylint: disable=invalid-name
    extracts: types.Extracts,
    new_features_fn: Callable[[types.FeaturesPredictionsLabels],
                              types.DictOfFetchedTensorValues]
) -> types.Extracts:
  """Augments FPL dict with new feature(s)."""
  # Create a new feature from existing ones.
  fpl_copy = get_fpl_copy(extracts)
  new_features = new_features_fn(fpl_copy)
  # Add the new features to the existing ones.
  update_fpl_features(fpl_copy, new_features)
  result = copy.copy(extracts)
  result[constants.FEATURES_PREDICTIONS_LABELS_KEY] = fpl_copy
  return result