code: def test_gradcheck(self, kernel_size, device, dtype):
      batch_size, channels, height, width = 1, 2, 5, 4
      img = torch.rand(
          batch_size,
          channels,
          height,
          width,
          device=device,
          dtype=dtype,
      )
      img = tensor_to_gradcheck_var(img)  # to var
      fast_mode = "cpu" in str(device)  # Disable fast mode for GPU
      self.gradcheck(box_blur, (img, kernel_size), fast_mode=fast_mode)
  
file_path: kornia/test/filters/test_blur.py
imports: import pytest
  import torch
  from kornia.filters import BoxBlur, box_blur
  from kornia.testing import BaseTester, tensor_to_gradcheck_var
label_desc: Use image node_id 9 for calling the TestBoxBlur obj's underlying member method code with example usage: obj.test_gradcheck(kernel_size, device, dtype) without return types