def get_prev_marker(self):
        return http.urlquote_plus(self.get_object_id(self.data[0])) \
            if self.data else ''
Compute the gradient of the marginal likelihood for a given dataset wrt K
dataset/ETHPy150Open CiscoSystems/avos/horizon/tables/base.py/DataTable.get_prev_marker--crossover with--dataset/ETHPy150Open HIPS/pgmult/pgmult/gp.py/_MultinomialGPBase.grad_marg_likelihood