docstr: This test exists because `TestHeteroskedasticSingleTaskGP` inherits from
  `TestSingleTaskGP`, which has a `test_custom_init` method that isn't relevant
  for `TestHeteroskedasticSingleTaskGP`.
docstr_tok: ["This","test","exists","because","`","TestHeteroskedasticSingleTaskGP","`","inherits","from","`","TestSingleTaskGP","`",",","which","has","a","`","test_custom_init","`","method","that","is","n't","relevant","for","`","TestHeteroskedasticSingleTaskGP","`","."]
code: def test_custom_init(self) -> None:
      """
      This test exists because `TestHeteroskedasticSingleTaskGP` inherits from
      `TestSingleTaskGP`, which has a `test_custom_init` method that isn't relevant
      for `TestHeteroskedasticSingleTaskGP`.
      """
  
imports: import itertools
  import warnings
  import torch
  from botorch.exceptions.warnings import OptimizationWarning
  from botorch.fit import fit_gpytorch_mll
  from botorch.models.gp_regression import FixedNoiseGP, HeteroskedasticSingleTaskGP, SingleTaskGP
  from botorch.models.transforms import Normalize, Standardize
  from botorch.models.transforms.input import InputStandardize
  from botorch.posteriors import GPyTorchPosterior
  from botorch.sampling import SobolQMCNormalSampler
  from botorch.utils.datasets import SupervisedDataset
  from botorch.utils.sampling import manual_seed
  from botorch.utils.test_helpers import get_pvar_expected
  from botorch.utils.testing import _get_random_data, BotorchTestCase
  from gpytorch.kernels import MaternKernel, RBFKernel, ScaleKernel
  from gpytorch.likelihoods import _GaussianLikelihoodBase, FixedNoiseGaussianLikelihood, GaussianLikelihood, HeteroskedasticNoise
  from gpytorch.means import ConstantMean, ZeroMean
  from gpytorch.mlls.exact_marginal_log_likelihood import ExactMarginalLogLikelihood
  from gpytorch.mlls.noise_model_added_loss_term import NoiseModelAddedLossTerm
  from gpytorch.priors import GammaPrior
label_desc: Use image node_id 2 for calling the TestHeteroskedasticSingleTaskGP obj's underlying member method code with example usage: obj.test_custom_init() without return types