code: def test_predictive_ll_regression_error_delta(self):
      return self.test_regression_error(
          mll_cls=gpytorch.mlls.PredictiveLogLikelihood,
          distribution_cls=gpytorch.variational.DeltaVariationalDistribution,
      )
  
imports: import math
  import unittest
  import warnings
  from pathlib import Path
  from unittest.mock import MagicMock, patch
  import linear_operator
  import torch
  from torch import optim
  import gpytorch
  from gpytorch.likelihoods import GaussianLikelihood
  from gpytorch.models import ApproximateGP
  from gpytorch.test.base_test_case import BaseTestCase
  from gpytorch.test.utils import least_used_cuda_device
  from gpytorch.utils.warnings import OldVersionWarning
label_desc: Use image node_id 4 for calling the TestSVGPRegression obj's underlying member method code with example usage: obj.test_predictive_ll_regression_error_delta() and returns: self