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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 clear_credentials():
 """De-authenticate by clearing all the names back to None."""

    global identity, regions, services, cloudservers, cloudfiles, cloud_cdn
    global cloud_loadbalancers, cloud_databases, cloud_blockstorage, cloud_dns
    global cloud_networks, cloud_monitoring, autoscale, images, queues
    identity = None
    regions = tuple()
    services = tuple()
    cloudservers = None
    cloudfiles = None
    cloud_cdn = None
    cloud_loadbalancers = None
    cloud_databases = None
    cloud_blockstorage = None
    cloud_dns = None
    cloud_networks = None
    cloud_monitoring = None
    autoscale = None
    images = None
    queues = None