code: def confounding_vars(rng):
      return rng.standard_normal((N_SAMPLES, N_COVARS))
  
imports: import nibabel
  import numpy
  import pytest
  from numpy.testing import assert_array_almost_equal, assert_array_less, assert_equal
  from scipy import stats
  from nilearn.conftest import _rng
  from nilearn.maskers import NiftiMasker
  from nilearn.mass_univariate import permuted_ols
label_desc: Use image node_id 7 for calling a global function with example usage: confounding_vars(rng) and returns: rng