code: def _check_design_matrix(design_matrix):
      """Check design_matrix type."""
      if design_matrix is not None and not isinstance(
          design_matrix, pd.DataFrame
      ):
          raise ValueError("design matrix must be a pandas DataFrame")
  
imports: import sys
  import time
  from warnings import warn
  import numpy
  import pandas
  from joblib import Memory
  from nibabel import Nifti1Image
  from sklearn.base import clone
  from nilearn._utils import fill_doc, stringify_path
  from nilearn._utils.niimg_conversions import check_niimg
  from nilearn.glm._base import BaseGLM
  from nilearn.glm.contrasts import compute_contrast, expression_to_contrast_vector
  from nilearn.glm.first_level import FirstLevelModel, run_glm
  from nilearn.glm.first_level.design_matrix import make_second_level_design_matrix
  from nilearn.glm.regression import RegressionResults, SimpleRegressionResults
  from nilearn.image import mean_img
  from nilearn.maskers import NiftiMasker
  from nilearn.mass_univariate import permuted_ols
label_desc: Use image node_id 13 for calling a global function with example usage: _check_design_matrix(design_matrix) without return types