code: def test_unet_model(backbone):
      model = models.fastai.unet.model(
          num_classes=32,
          img_size=64,
          backbone=backbone(pretrained=True),
      )
  
      assert len(list(model.param_groups())) == 6
      assert model[-2][0].out_channels == 32
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_unet_model(backbone) without return types