class_docstr: Test download tools
code: def test_download1(self):
      download_from_url(self.url, "./", hash_prefix=None)
      self.assertTrue(os.path.isfile(self.target_file))
  
      download_from_url(self.url, "./", hash_prefix="7222f2e")
      self.assertTrue(os.path.isfile(self.target_file))
  
file_path: towhee/tests/unittests/models/utils/test_download.py
imports: import unittest
  import os
  from towhee.models.utils.download import download_from_url, checksum
label_desc: Use image node_id 2 for calling the TestDownload obj's underlying member method code with example usage: obj.test_download1() without return types