code: def test_initialize_power_prior(self):
      kernel = DownsamplingKernel()
      kernel.power_prior = NormalPrior(1, 1)
      self.assertTrue(isinstance(kernel.power_prior, NormalPrior))
      kernel2 = DownsamplingKernel(power_prior=GammaPrior(1, 1))
      self.assertTrue(isinstance(kernel2.power_prior, GammaPrior))
  
imports: import torch
  from botorch.models.kernels.downsampling import DownsamplingKernel
  from botorch.utils.testing import BotorchTestCase
  from gpytorch.priors.torch_priors import GammaPrior, NormalPrior
  from gpytorch.test.base_kernel_test_case import BaseKernelTestCase
label_desc: Use image node_id 17 for calling the TestDownsamplingKernel obj's underlying member method code with example usage: obj.test_initialize_power_prior() without return types