code: def test_nondiag(tpl_img, in_tmp_path):
      tpl_img.affine[0, 1] = 3.0
      save_image(tpl_img, "img.nii")
      img2 = load_image("img.nii")
      assert_almost_equal(img2.affine, tpl_img.affine)
  
imports: from os.path import dirname
  from os.path import join
  import nibabel
  import numpy
  import pytest
  from nibabel import Nifti1Header
  from nibabel.filebasedimages import ImageFileError
  from nibabel.spatialimages import HeaderDataError
  from nibabel.tests.test_round_trip import big_bad_ulp
  from nipy.core.api import AffineTransform
  from nipy.core.api import Image, vox2mni
  from nipy.testing import anatfile, assert_almost_equal, assert_array_almost_equal, assert_array_equal, funcfile
  from nipy.testing.decorators import if_templates
  from nipy.utils import DataError, templates
  from ..api import as_image, load_image, save_image
label_desc: Use image node_id 4 for calling a global function with example usage: test_nondiag(tpl_img, in_tmp_path) without return types