code: def prepare_is_roi(test_dict):
      """Prepare calculated and expected check for region of interest data for equal checking."""
      earth_model = 2
      dataset_id = make_dataid(name="VIS006")
      is_full_disk = test_dict["is_full_disk"]
      is_rapid_scan = test_dict["is_rapid_scan"]
      header = create_test_header(
          earth_model, dataset_id, is_full_disk, is_rapid_scan
      )
      trailer = create_test_trailer(is_rapid_scan)
      expected = test_dict["is_roi"]
  
      with mock.patch(
          "satpy.readers.seviri_l1b_native.np.fromfile"
      ) as fromfile, mock.patch(
          "satpy.readers.seviri_l1b_native.recarray2dict"
      ) as recarray2dict, mock.patch(
          "satpy.readers.seviri_l1b_native.NativeMSGFileHandler._get_memmap"
      ) as _get_memmap, mock.patch(
          "satpy.readers.seviri_l1b_native.NativeMSGFileHandler._read_trailer"
      ), mock.patch(
          "satpy.readers.seviri_l1b_native.has_archive_header"
      ) as has_archive_header:
          has_archive_header.return_value = True
          fromfile.return_value = header
          recarray2dict.side_effect = lambda x: x
          _get_memmap.return_value = np.arange(3)
          fh = NativeMSGFileHandler(
              filename=None, filename_info={}, filetype_info=None
          )
          fh.header = header
          fh.trailer = trailer
          actual = fh.is_roi()
  
      return actual, expected
  
imports: from __future__ import annotations
  import os
  import unittest
  import warnings
  from datetime import datetime
  from unittest import mock
  import dask.array
  import numpy
  import pytest
  import xarray
  from satpy.readers.eum_base import recarray2dict, time_cds_short
  from satpy.readers.seviri_l1b_native import ASCII_STARTSWITH, ImageBoundaries, NativeMSGFileHandler, Padder, get_available_channels, has_archive_header
  from satpy.tests.reader_tests.test_seviri_base import ORBIT_POLYNOMIALS, ORBIT_POLYNOMIALS_INVALID
  from satpy.tests.reader_tests.test_seviri_l1b_calibration import TestFileHandlerCalibrationBase
  from satpy.tests.utils import assert_attrs_equal, make_dataid
label_desc: Use image node_id 6 for calling a global function with example usage: prepare_is_roi(test_dict) and returns: actual,  expected