code: def test_pretrained_weights_registry(
      backbone, pretrained, expected_num_features
  ):
      backbone_fn = IMAGE_CLASSIFIER_BACKBONES.get(backbone)
      backbone_model, num_features = backbone_fn(pretrained=pretrained)
      assert backbone_model
      assert num_features == expected_num_features
  
file_path: lightning-flash/tests/image/test_backbones.py
imports: import urllib.error
  import pytest
  from flash.core.utilities.imports import _TOPIC_IMAGE_AVAILABLE
  from flash.core.utilities.url_error import catch_url_error
  from flash.image.classification.backbones import IMAGE_CLASSIFIER_BACKBONES
label_desc: Use image node_id 2 for calling a global function with example usage: test_pretrained_weights_registry(backbone, pretrained, expected_num_features) without return types