class_docstr: Unittest for repo normalize.
code: def test_mapping(self):
      with self.assertRaises(ValueError):
          RepoNormalize.mapping("resnet_image_embedding[pytorch")
  
file_path: towhee/tests/unittests/utils/test_repo_normalize.py
imports: import unittest
  from towhee.utils.repo_normalize import RepoNormalize
label_desc: Use image node_id 4 for calling the TestRepoNormalize obj's underlying member method code with example usage: obj.test_mapping() without return types