docstr: Add io_state to poller.
docstr_tok: ["Add","io_state","to","poller","."]
code: def _add_io_state(self, state):
      """Add io_state to poller."""
      if self._state != state:
          state = self._state = self._state | state
      self._update_handler(self._state)
  
imports: from collections import namedtuple, deque
  from itertools import chain
  from zmq import EVENTS, POLLOUT, POLLIN
  import zmq
label_desc: Use image node_id 20 for calling the _AsyncSocket obj's underlying member method code with example usage: obj._add_io_state(state) without return types