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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 _load_relation(self, models, name, constraints):
 """ Eagerly load the relationship on a set of models. :rtype: list """

        relation = self.get_relation(name)

        relation.add_eager_constraints(models)

        if callable(constraints):
            constraints(relation)
        else:
            relation.merge_query(constraints)

        models = relation.init_relation(models, name)

        results = relation.get_eager()

        return relation.match(models, results, name)