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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 service_restart(service_name):
 """ Wrapper around host.service_restart to prevent spurious "unknown service" messages in the logs. """

    if host.service_available(service_name):
        if host.service_running(service_name):
            host.service_restart(service_name)
        else:
            host.service_start(service_name)