Called by IOLoop when there is activity on one of our
        file descriptors.

def _handle_events(self, fd: int, events: int) -> None:
        """Called by IOLoop when there is activity on one of our
        file descriptors.
        """
        action = 0
        if events & ioloop.IOLoop.READ:
            action |= pycurl.CSELECT_IN
        if events & ioloop.IOLoop.WRITE:
            action |= pycurl.CSELECT_OUT
        while True:
            try:
                ret, num_handles = self._multi.socket_action(fd, action)
            except pycurl.error as e:
                ret = e.args[0]
            if ret != pycurl.E_CALL_MULTI_PERFORM:
                break
        self._finish_pending_requests()