code: def test_unregister_closed(self):
      server, client = self._connected_pair()
      fd = server.fileno()
      ep = select.epoll(16)
      ep.register(server)
  
      now = time.monotonic()
      events = ep.poll(1, 4)
      then = time.monotonic()
      self.assertFalse(then - now > 0.01)
  
      server.close()
  
      with self.assertRaises(OSError) as cm:
          ep.unregister(fd)
      self.assertEqual(cm.exception.errno, errno.EBADF)
  
imports: import errno
  import os
  import select
  import socket
  import time
  import unittest
  from test import support
label_desc: Use image node_id 11 for calling the TestEPoll obj's underlying member method code with example usage: obj.test_unregister_closed() without return types