def _add_pret_words(self, pret_embeddings):
words_in_train_data = set(self._id2word)<EOL>pret_embeddings = gluonnlp.embedding.create(pret_embeddings[<NUM_LIT:0>], source=pret_embeddings[<NUM_LIT:1>])<EOL>for idx, token in enumerate(pret_embeddings.idx_to_token):<EOL><INDENT>if token not in words_in_train_data:<EOL><INDENT>self._id2word.append(token)<EOL><DEDENT><DEDENT>
Read pre-trained embedding file for extending vocabulary

        Parameters
        ----------
        pret_embeddings : tuple
            (embedding_name, source), used for gluonnlp.embedding.create(embedding_name, source)