code: def test_gradcheck(self, device, dtype):
      img = torch.rand(1, 2, 5, 4, device=device, dtype=dtype)
      img = utils.tensor_to_gradcheck_var(img)  # to var
      assert gradcheck(
          kornia.geometry.pyrup,
          (img,),
          nondet_tol=1e-8,
          raise_exception=True,
          fast_mode=True,
      )
  
imports: import pytest
  import torch
  from torch.autograd import gradcheck
  import kornia
  import kornia.testing
  from kornia.testing import BaseTester, assert_close
label_desc: Use image node_id 3 for calling the TestPyrUp obj's underlying member method code with example usage: obj.test_gradcheck(device, dtype) without return types