code: def test_show_constrast():
      # test that the show code indeed (formally) runs
      frametimes = np.linspace(0, 127 * 1.0, 128)
      DM = make_dmtx(
          frametimes, drift_model="polynomial", drift_order=3
      )
      contrast = np.random.standard_normal((3, DM.matrix.shape[1]))
      ax = DM.show_contrast(contrast)
      assert ax is not None
  
      # test the colormap
      ax = DM.show_contrast(contrast, cmap=matplotlib.pyplot.cm.gray)
      assert ax is not None
  
imports: import os.path
  from unittest import skipIf
  import numpy
  from numpy.testing import assert_almost_equal, assert_array_equal
  from ..design_matrix import _convolve_regressors, _cosine_drift, dmtx_from_csv, dmtx_light, make_dmtx
  from ..experimental_paradigm import BlockParadigm, EventRelatedParadigm
label_desc: Use image node_id 7 for calling a global function with example usage: test_show_constrast() without return types