code: def test_shape_custom_factor(self, device, dtype):
      inp = torch.zeros(1, 2, 9, 9, device=device, dtype=dtype)
      pyr = kornia.geometry.PyrDown(factor=3.0)
      assert pyr(inp).shape == (1, 2, 3, 3)
  
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 2 for calling the TestPyrDown obj's underlying member method code with example usage: obj.test_shape_custom_factor(device, dtype) without return types