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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _add_pret_words(self, pret_embeddings):
 """Read pre-trained embedding file for extending vocabulary Parameters pret_embeddings : tuple (embedding_name, source), used for gluonnlp.embedding.create(embedding_name, source) """

        words_in_train_data = set(self._id2word)
        pret_embeddings = gluonnlp.embedding.create(pret_embeddings[0], source=pret_embeddings[1])

        for idx, token in enumerate(pret_embeddings.idx_to_token):
            if token not in words_in_train_data:
                self._id2word.append(token)