code: def _ensure_systemd(version):
      '''
      Raises an exception if the systemd version is not greater than the
      passed version.
      '''
      try:
          version = int(version)
      except ValueError:
          raise CommandExecutionError('Invalid version \'{0}\''.format(version))
  
      try:
          installed = _sd_version()
          log.debug('nspawn: detected systemd %s', installed)
      except (IndexError, ValueError):
          raise CommandExecutionError('nspawn: Unable to get systemd version')
  
      if installed < version:
          raise CommandExecutionError(
              'This function requires systemd >= {0} '
              '(Detected version: {1}).'.format(version, installed)
          f _ensure_systemd(version):
      '''
      Raises an exception if the systemd version is not greater than the
      passed version.
      '''
      try:
          version = int(version)
      except ValueError:
          raise CommandExecutionError('Invalid version \'{0}\''.format(version))
  
      try:
          installed = _sd_version()
          log.debug('nspawn: detected systemd %s', installed)
      except (IndexError, ValueError):
          raise CommandExecutionError('nspawn: Unable to get systemd version')
  
      if installed < version:
          raise CommandExecutionError(
              'This function requires systemd >= {0} '
              '(Detected version: {1}).'.format(version, installed)
          )
docs: Raises an exception if the systemd version is not greater than the
      passed version.