docstr: unregister the ioloop event handler
  
  called once during close
docstr_tok: ["unregister","the","ioloop","event","handler","called","once","during","close"]
code: def _clear_io_state(self):
      """unregister the ioloop event handler
  
      called once during close
      """
      fd = self._shadow_sock
      if self._shadow_sock.closed:
          fd = self._fd
      self.io_loop.remove_handler(fd)
  
imports: from collections import namedtuple, deque
  from itertools import chain
  from zmq import EVENTS, POLLOUT, POLLIN
  import zmq
label_desc: Use image node_id 24 for calling the _AsyncSocket obj's underlying member method code with example usage: obj._clear_io_state() without return types