Predict the relation of two sentences.

        Parameters
        ----------
        sentence1 : NDArray
            Shape (batch_size, length)
        sentence2 : NDArray
            Shape (batch_size, length)

        Returns
        -------
        pred : NDArray
            Shape (batch_size, num_classes). num_classes == 3.

def hybrid_forward(self, F, sentence1, sentence2):
        """
        Predict the relation of two sentences.

        Parameters
        ----------
        sentence1 : NDArray
            Shape (batch_size, length)
        sentence2 : NDArray
            Shape (batch_size, length)

        Returns
        -------
        pred : NDArray
            Shape (batch_size, num_classes). num_classes == 3.

        """
        feature1 = self.lin_proj(self.word_emb(sentence1))
        feature2 = self.lin_proj(self.word_emb(sentence2))
        if self.use_intra_attention:
            feature1 = F.concat(feature1, self.intra_attention(feature1), dim=-1)
            feature2 = F.concat(feature2, self.intra_attention(feature2), dim=-1)
        pred = self.model(feature1, feature2)
        return pred