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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 rmq_wait_for_cluster(self, deployment, init_sleep=15, timeout=1200):
 """Wait for rmq units extended status to show cluster readiness, after an optional initial sleep period. Initial sleep is likely necessary to be effective following a config change, as status message may not instantly update to non-ready."""


        if init_sleep:
            time.sleep(init_sleep)

        message = re.compile('^Unit is ready and clustered$')
        deployment._auto_wait_for_status(message=message,
                                         timeout=timeout,
                                         include_only=['rabbitmq-server'])