code: def test_ftp(self):
      # Testing the same URL twice exercises the caching in CacheFTPHandler
      urls = [
          "ftp://www.pythontest.net/README",
          "ftp://www.pythontest.net/README",
          (
              "ftp://www.pythontest.net/non-existent-file",
              None,
              urllib.error.URLError,
          ),
      ]
      self._test_urls(urls, self._extra_handlers())
  
imports: import errno
  import unittest
  from test import support
  from test.support import os_helper
  from test.support import socket_helper
  from test.support import ResourceDenied
  from test.test_urllib2 import sanepathname2url
  import os
  import socket
  import urllib.error
  import urllib.request
  import sys
label_desc: Use image node_id 2 for calling the OtherNetworkTests obj's underlying member method code with example usage: obj.test_ftp() without return types