code: def test_back_and_forth_rgb(self, device, dtype):
      a_val: float = 1.0
      x_rgb = torch.ones(3, 4, 4, device=device, dtype=dtype)
      x_rgba = kornia.color.rgb_to_rgba(x_rgb, a_val)
      x_rgb_new = kornia.color.rgba_to_rgb(x_rgba)
      self.assert_close(x_rgb, x_rgb_new)
  
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 TestRgbToRgba obj's underlying member method code with example usage: obj.test_back_and_forth_rgb(device, dtype) without return types