Remove interest in IO events from the specified fileobj

        :param fileobj:
            Any existing file-like object that has a fileno() method and was
            previously registered with :meth:`register()`
        :raises ValueError:
            if `fileobj` is invalid or not supported
        :raises KeyError:
            if the descriptor associated with `fileobj` is not registered.
        :returns:
            A :class:`SelectorKey` associated with the passed arguments

def unregister(self, fileobj):
        """
        Remove interest in IO events from the specified fileobj

        :param fileobj:
            Any existing file-like object that has a fileno() method and was
            previously registered with :meth:`register()`
        :raises ValueError:
            if `fileobj` is invalid or not supported
        :raises KeyError:
            if the descriptor associated with `fileobj` is not registered.
        :returns:
            A :class:`SelectorKey` associated with the passed arguments
        """
        fd = _get_fd(fileobj)
        key = self._fd_map[fd]
        try:
            self._epoll.unregister(fd)
        except OSError:
            pass
        del self._fd_map[fd]
        return key