code: def encode_tf(self, s):
      
      ids = subword_text_encoder_ops.subword_text_encoder_encode(
          s, self._filepath)
      # the c++ op apppends 1=EOS - drop it.
      return ids[:-1]
docs: Encode a tf.Scalar string to a tf.Tensor.
  
      This will be necessary for on-the-fly tokenization.
  
      Args:
        s: a tf.Scalar with dtype tf.string
      Returns:
        a 1d tf.Tensor with dtype tf.int32