<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def handle_ChannelCloseOK(self, frame):
 """ AMQP server closed channel as per our request """

        assert self.channel._closing, "received a not expected CloseOk"
        # Release the `close` method's future
        self.synchroniser.notify(spec.ChannelCloseOK)

        exc = ChannelClosed()
        self._close_all(exc)