code: def test_unit_white(self, device, dtype):  # skipcq: PYL-R0201
      rgb = (
          torch.tensor(
              [
                  [[255, 255], [255, 255]],
                  [[255, 255], [255, 255]],
                  [[255, 255], [255, 255]],
              ],
              device=device,
              dtype=torch.uint8,
          ).type(dtype)
          / 255.0
      )
      refy = torch.tensor(
          [[[255, 255], [255, 255]]], device=device, dtype=torch.uint8
      )
      refuv = torch.tensor(
          [[[0]], [[0]]], device=device, dtype=torch.int8
      )
  
      resy = (
          (kornia.color.rgb_to_yuv420(rgb)[0] * 255.0)
          .round()
          .type(torch.uint8)
      )
      resuv = (
          (kornia.color.rgb_to_yuv420(rgb)[1] * 255.0)
          .round()
          .clamp(-128, 127)
          .type(torch.int8)
      )
      self.assert_close(refy, resy)
      self.assert_close(refuv, resuv)
  
imports: import pytest
  import torch
  from torch.autograd import gradcheck
  import kornia
  from kornia.testing import BaseTester
label_desc: Use image node_id 4 for calling the TestRgbToYuv420 obj's underlying member method code with example usage: obj.test_unit_white(device, dtype) without return types