human
Solve the following python programming problem given the following code:
def assert_expected_deployment(self, cluster, expected_deployment) : 
    '
        Assert that the expected set of ``Application`` instances on a set of
        nodes is the same as the actual set of ``Application`` instance on
        those nodes.

        The tutorial looks at Docker output, but the acceptance tests are
        intended to test high-level external behaviors. Since this is looking
        at the output of the control service API it merely verifies what
        Flocker believes the system state is, not the actual state.
        The latter should be verified separately with additional tests
        for external side-effects (applications being available on ports,
        say).

        :param cluster: The ``Cluster`` to query for current configuration.
        :param dict expected_deployment: A mapping of IP addresses to set of
            ``Application`` instances expected on the nodes with those IP
            addresses.

        :return Deferred: Fires on end of assertion.
        ' 
    ip_to_uuid = { node.reported_hostname : node.uuid for node in cluster.nodes } 
    def got_results(existing_containers) : 
        expected = [] 
        for (reported_hostname, apps) in expected_deployment.items () : 
            node_uuid = ip_to_uuid [reported_hostname] 
            expected += [container_configuration_response (app, node_uuid) for app in apps] 
for app in expected : 
            app ['running'] = True 
return (sorted (existing_containers) == sorted (expected)) 
def configuration_matches_state() : 
        d = cluster.current_containers () 
        d.addCallback (got_results) 
        return d 
return loop_until (reactor, <MASK>) 
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here
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def configuration_matches_state(