code: def test_tensor_difference(self) -> None:
      n, m = 3, 2
      A = torch.arange(n * m).reshape(n, m)
      B = torch.cat((A[: n - 1], torch.randn(2, m)), dim=0)
      # permute B
      B = B[torch.randperm(len(B))]
  
      C = _tensor_difference(A=A, B=B)
  
      self.assertEqual(C.size(dim=0), 2)
  
imports: import warnings
  from typing import OrderedDict
  import numpy
  import torch
  from ax.core.search_space import SearchSpaceDigest
  from ax.exceptions.core import AxError, AxWarning, UnsupportedError
  from ax.models.torch.botorch_modular.utils import _get_shared_rows, _tensor_difference, check_metric_dataset_match, choose_botorch_acqf_class, choose_model_class, construct_acquisition_and_optimizer_options, convert_to_block_design, get_subset_datasets, subset_state_dict, use_model_list
  from ax.models.torch.utils import _to_inequality_constraints
  from ax.utils.common.constants import Keys
  from ax.utils.common.testutils import TestCase
  from ax.utils.common.typeutils import checked_cast, not_none
  from ax.utils.testing.torch_stubs import get_torch_test_data
  from botorch.acquisition import qLogNoisyExpectedImprovement
  from botorch.acquisition.multi_objective.logei import qLogNoisyExpectedHypervolumeImprovement
  from botorch.models.fully_bayesian import SaasFullyBayesianSingleTaskGP
  from botorch.models.gp_regression import SingleTaskGP
  from botorch.models.gp_regression_fidelity import SingleTaskMultiFidelityGP
  from botorch.models.gp_regression_mixed import MixedSingleTaskGP
  from botorch.models.model_list_gp_regression import ModelListGP
  from botorch.models.multitask import MultiTaskGP
  from botorch.utils.datasets import SupervisedDataset
label_desc: Use image node_id 9 for calling the BoTorchModelUtilsTest obj's underlying member method code with example usage: obj.test_tensor_difference() without return types