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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 review_score(self, reviewer, product):
 """Find a review score from a given reviewer to a product. Args: reviewer: Reviewer i.e. an instance of :class:`ria.bipartite.Reviewer`. product: Product i.e. an instance of :class:`ria.bipartite.Product`. Returns: A review object representing the review from the reviewer to the product. """

        return self._g.retrieve_review(reviewer, product).score