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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 config_get(option_name):
 """ Helper to access a Juju config option when charmhelpers is not available. :param str option_name: Name of the config option to get the value of """

    try:
        raw = subprocess.check_output(['config-get', option_name, '--format=yaml'])
        return yaml.load(raw.decode('UTF-8'))
    except ValueError:
        return None