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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 authenticate(cls, client_id, secret):
 """ Authenticate a client using it's secret :param client_id: the client / service ID :param secret: the client secret :returns: a Service instance """

        result = yield views.oauth_client.get(key=[secret, client_id])
        if not result['rows']:
            raise Return()

        service = yield Service.get(client_id)
        raise Return(service)