code: def test_smoke_double_batch_kernel_double_batch_x(self):
      x = self.create_data_double_batch()
      kernel = self.create_kernel(
          num_dims=x.size(-1), batch_shape=torch.Size([3, 2])
      )
      y = torch.randn_like(x[..., 0])
      kernel.initialize_from_data(x, y)
      kernel.initialize_from_data_empspect(x, y)
  
      batch_covar_mat = kernel(x).evaluate_kernel().to_dense()
      kernel_diag = kernel(x, diag=True)
      return batch_covar_mat, kernel_diag
  
file_path: gpytorch/test/kernels/test_spectral_mixture_kernel.py
imports: import unittest
  import torch
  from gpytorch.kernels import SpectralMixtureKernel
label_desc: Use image node_id 9 for calling the TestSpectralMixtureKernel obj's underlying member method code with example usage: obj.test_smoke_double_batch_kernel_double_batch_x() and returns: batch_covar_mat,  kernel_diag