Return a dict for encoding and decoding inference input/output.

    Args:
      data_dir: data directory

    Returns:
      A dict of <feature name, TextEncoder>.

def feature_encoders(self, data_dir):
    """Return a dict for encoding and decoding inference input/output.

    Args:
      data_dir: data directory

    Returns:
      A dict of <feature name, TextEncoder>.

    """
    encoders = (super(BabiQa, self).feature_encoders(data_dir))
    label_encoder = self.get_labels_encoder(data_dir)
    encoders["targets"] = label_encoder  # bAbi as a classification task
    return encoders