import tensorflow as tf

        dtypes = {"feature": tf.int64, "src_lang": tf.int64, "trg_lang": tf.int64}
        signatures = {"feature": tf.TensorShape([None, None]),
                      "src_lang": tf.TensorShape([None, ]),
                      "trg_lang": tf.TensorShape([None, ])}
        if mode == compat.ModeKeys.INFER:
            return dtypes, signatures
        dtypes["label"] = tf.int64
        signatures["label"] = tf.TensorShape([None, None])
        return dtypes, signatures

    def build_model(self, args, name=None):
        """ Builds and return a keras model. """
        model = build_model(args, self._multilingual_dp.meta,
                            self._multilingual_dp.meta, name=name)
