docs: def update_persistent_boot(self, devices=[], persistent=False):
          """Changes the persistent boot device order in BIOS boot mode for host
  
          Note: It uses first boot device from the devices and ignores rest.
  
          :param devices: ordered list of boot devices
          :param persistent: Boolean flag to indicate if the device to be set as
                             a persistent boot device
          :raises: IloError, on an error from iLO.
          :raises: IloInvalidInputError, if the given input is not valid.
          """
          device = PERSISTENT_BOOT_DEVICE_MAP.get(devices[0].upper())
          if device == sushy.BOOT_SOURCE_TARGET_UEFI_TARGET:
              try:
                  uefi_devices = self.uefi_target_override_devices
                  iscsi_device = None
                  for uefi_device in uefi_devices:
                      if uefi_device is not None and 'iSCSI' in uefi_device:
                          iscsi_device = uefi_device
                          break
  
                  if iscsi_device is None:
                      msg = 'No UEFI iSCSI bootable device found on system.'
                      raise exception.IloError(msg)
  
              except sushy.exceptions.SushyError as e:
                  msg = ('Unable to get uefi target override devices. '
                         'Error %s') % (str(e))
                  raise exception.IloError(msg)
  
              uefi_boot_settings = {
                  'Boot': {'UefiTargetBootSourceOverride': iscsi_device}
              }
              self._conn.patch(self.path, data=uefi_boot_settings)
          elif device is None:
              device = sushy.BOOT_SOURCE_TARGET_NONE
  
          tenure = (sushy.BOOT_SOURCE_ENABLED_CONTINUOUS
                    if persistent else sushy.BOOT_SOURCE_ENABLED_ONCE)
          self.set_system_boot_source(device, enabled=tenure)