class_docstr: Simple hub download and run test.
code: def test_download_op(self):
      with TemporaryDirectory(dir="./") as root:
          download_operator("image-decode", "cv2-rgb", "main", root)
          op_root = Path(root)
          self.assertTrue((op_root / "files").is_dir())
          self.assertTrue((op_root / "versions" / "main").is_dir())
  
imports: import unittest
  from pathlib import Path
  from tempfile import TemporaryDirectory
  from towhee.hub.downloader import _HubFiles, download_operator, repo_tag_path
label_desc: Use image node_id 2 for calling the TestDownloader obj's underlying member method code with example usage: obj.test_download_op() without return types