code: def affine_mni():
      """Return an affine corresponding to 2mm isotropic MNI template."""
      return _affine_mni()
  
imports: import warnings
  import nibabel
  import numpy
  import pytest
  from nibabel import Nifti1Image
  from nilearn import image
  from nilearn.datasets.tests._testing import request_mocker
  from nilearn.datasets.tests._testing import temp_nilearn_data_dir
  from nilearn.experimental.surface.tests.conftest import make_mini_img, mini_img, mini_mesh
label_desc: Use image node_id 8 for calling a global function with example usage: affine_mni() and returns: _affine_mni