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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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