docs: 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