code: def test_initialize_covar_module(self):
      kernel = LinearTruncatedFidelityKernel(
          fidelity_dims=[1, 2], dimension=3
      )
      self.assertTrue(
          isinstance(kernel.covar_module_unbiased, MaternKernel)
      )
      self.assertTrue(
          isinstance(kernel.covar_module_biased, MaternKernel)
      )
      kernel.covar_module_unbiased = RBFKernel()
      kernel.covar_module_biased = RBFKernel()
      self.assertTrue(
          isinstance(kernel.covar_module_unbiased, RBFKernel)
      )
      self.assertTrue(isinstance(kernel.covar_module_biased, RBFKernel))
      kernel2 = LinearTruncatedFidelityKernel(
          fidelity_dims=[1, 2],
          dimension=3,
          covar_module_unbiased=RBFKernel(),
          covar_module_biased=RBFKernel(),
      )
      self.assertTrue(
          isinstance(kernel2.covar_module_unbiased, RBFKernel)
      )
      self.assertTrue(
          isinstance(kernel2.covar_module_biased, RBFKernel)
      )
  
imports: import itertools
  import torch
  from botorch.exceptions import UnsupportedError
  from botorch.models.kernels.linear_truncated_fidelity import LinearTruncatedFidelityKernel
  from botorch.utils.testing import BotorchTestCase
  from gpytorch.kernels.matern_kernel import MaternKernel
  from gpytorch.kernels.rbf_kernel import RBFKernel
  from gpytorch.priors.torch_priors import GammaPrior, NormalPrior
  from gpytorch.test.base_kernel_test_case import BaseKernelTestCase
label_desc: Use image node_id 15 for calling the TestLinearTruncatedFidelityKernel obj's underlying member method code with example usage: obj.test_initialize_covar_module() without return types