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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 get_timeout(service):
 """ Returns either a custom timeout for the given service, or a default """

    custom_timeout_key = "RESTCLIENTS_%s_TIMEOUT" % service.upper()
    if hasattr(settings, custom_timeout_key):
        return getattr(settings, custom_timeout_key)

    default_key = "RESTCLIENTS_DEFAULT_TIMEOUT"
    if hasattr(settings, default_key):
        return getattr(settings, default_key)

    return OLD_DEFAULT_TIMEOUT