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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 mapping(self):
 """ Return the constructed mappings. Invert these to map internal indices to external ids. Returns ------- (user id map, user feature map, item id map, item id map):
 tuple of dictionaries """


        return (
            self._user_id_mapping,
            self._user_feature_mapping,
            self._item_id_mapping,
            self._item_feature_mapping,
        )