def _fetch_movies(self):
        """
        Fetch data and save in the pytorch format
            1. Read the train/test data from raw archive
            2. Parse train data
            3. Parse test data
            4. Save in the .pt with torch.save
        """
        data = self._read_raw_movielens_data()
        train_raw = data[0]
        test_raw = data[1]

        train_parsed = self._parse(train_raw)
        test_parsed = self._parse(test_raw)

        num_users, num_items = self._get_dimensions(train_parsed, test_parsed)

        train = self._build_interaction_matrix(
            num_users, num_items, self._parse(train_raw)
        )
        test = self._build_interaction_matrix(
            num_users, num_items, self._parse(test_raw)
        )
        assert train.shape == test.shape

        with open(os.path.join(self.processed_folder, self.training_file), "wb") as f:
            torch.save(train, f)

        with open(os.path.join(self.processed_folder, self.test_file), "wb") as f:
            torch.save(test, f)

        Fetch data and save in the pytorch format
            1. Read the train/test data from raw archive
            2. Parse train data
            3. Parse test data
            4. Save in the .pt with torch.save
        
catalyst/contrib/datasets/movielens.py