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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 top_referrers(self, domain_only=True):
 """ What domains send us the most traffic? """

        referrer = self._referrer_clause(domain_only)
        return (self.get_query()
                .select(referrer, fn.Count(PageView.id))
                .group_by(referrer)
                .order_by(fn.Count(PageView.id).desc())
                .tuples())