How to zmq.poll() some socket and some sort of variable?

I'm attempting to poll a few sockets and a multiprocessing.Event
The documentation states:

A zmq.Socketor any Python object having a fileno() method that returns a valid file descriptor.

which means that I can't use my Event but I should be able to use a file(as returned from open(...) or an io object (anything from the io library), but I'm having no success:

Traceback (most recent call last):  File "C:\Program Files\JetBrains\PyCharm Community Edition 2017.3\helpers\pydev\pydevd.py", line 1683, in <module>    main()  File "C:\Program Files\JetBrains\PyCharm Community Edition 2017.3\helpers\pydev\pydevd.py", line 1677, in main    globals = debugger.run(setup['file'], None, None, is_module)  File "C:\Program Files\JetBrains\PyCharm Community Edition 2017.3\helpers\pydev\pydevd.py", line 1087, in run    pydev_imports.execfile(file, globals, locals)  # execute the script  File "C:\Program Files\JetBrains\PyCharm Community Edition 2017.3\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile    exec(compile(contents+"\n", file, 'exec'), glob, loc)  File "C:\work\polldamnyou.py", line 122, in <module>    p = poller.poll(1000)  File "C:\WinPython-64bit-3.6.3.0Qt5\python-3.6.3.amd64\Lib\site-packages\zmq\sugar\poll.py", line 99, in poll    return zmq_poll(self.sockets, timeout=timeout)  File "zmq\backend\cython\_poll.pyx", line 143, in zmq.backend.cython._poll.zmq_poll  File "zmq\backend\cython\_poll.pyx", line 123, in zmq.backend.cython._poll.zmq_poll  File "zmq\backend\cython\checkrc.pxd", line 25, in zmq.backend.cython.checkrc._check_rczmq.error.ZMQError: Unknown error

I have found the same question asked before but the solution was to use another socket which is sidestepping the problem. I am curious and want to see this working. Does any one have any clues what sort of object can be used in zmq.Poller other than a socket?

Edit: a few things I've tried

import traceback, os, zmqdef poll(poller):    try:        print('polled: ', poller.poll(3))    except zmq.error.ZMQError as e:        traceback.print_exc()class Pollable:    def __init__(self):        self.fd = os.open('dump', os.O_RDWR | os.O_BINARY)        self.FD = self.fd        self.events = 0        self.EVENTS = 0        self.revents = 0        self.REVENTS = 0    def fileno(self):        return self.fd    def __getattribute__(self, item):        if item != '__class__':            print("requested: ", item)        return super().__getattribute__(item)ctx = zmq.Context()sock = ctx.socket(zmq.SUB)poller = zmq.Poller()poller.register(sock, zmq.POLLIN)poll(poller)  # worksfile = open('dump', 'w+b')print("fileno: ", file.fileno())poller.register(file, zmq.POLLIN)poll(poller)  # failsfile.events = 0file.revents = 0file.EVENTS = 0file.REVENTS = 0file.fd = file.fileno()file.FD = file.fileno()poll(poller)  # still failspoller.unregister(file)file.close()poll(poller)  # worksfd = os.open('dump', os.O_RDWR|os.O_BINARY)print("fd: ", fd)dummy = Pollable()poller.register(dummy, zmq.POLLIN)poll(poller)  # fails

__getattribute__ shows that that fd and fileno are being accessed, but nothing else, so what is still wrong?!