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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 update_model(self, words):
 """ Updates the completer model. :param words: Words to update the completer with. :type words: tuple or list :return: Method success. :rtype: bool """


        extended_words = DefaultCompleter._DefaultCompleter__tokens[self.__language][:]
        extended_words.extend((word for word in set(words)
                               if word not in DefaultCompleter._DefaultCompleter__tokens[self.__language]))
        self.setModel(QStringListModel(extended_words))
        return True