code: def parameters_changed(self):
          
          self.Y_normalized[:] = self.transform_data()
          super(WarpedGP, self).parameters_changed()
          Kiy = self.posterior.woodbury_vector.flatten()
          self.warping_function.update_grads(self.Y_untransformed, Kiy)
docs: Notice that we update the warping function gradients here.