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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 update_cost_model(self, x, cost_x):
 """ Updates the GP used to handle the cost. param x: input of the GP for the cost model. param x_cost: values of the time cost at the input locations. """


        if self.cost_type == 'evaluation_time':
            cost_evals = np.log(np.atleast_2d(np.asarray(cost_x)).T)

            if self.num_updates == 0:
                X_all = x
                costs_all = cost_evals
            else:
                X_all = np.vstack((self.cost_model.model.X,x))
                costs_all = np.vstack((self.cost_model.model.Y,cost_evals))

            self.num_updates += 1
            self.cost_model.updateModel(X_all, costs_all, None, None)