code: def test_coeff_of_determination(rng):
      model = rng.standard_normal((10, 10, 10, 150))
      data = np.copy(model)
      # If the model predicts the data perfectly, the COD is all 100s:
      cod = xval.coeff_of_determination(data, model)
      npt.assert_array_equal(100, cod)
  
file_path: dipy/dipy/reconst/tests/test_cross_validation.py
imports: import warnings
  import numpy
  import numpy.testing
  import dipy.reconst.cross_validation
  import dipy.data
  import dipy.reconst.dti
  import dipy.core.gradients
  import dipy.sims.voxel
  import dipy.reconst.csdeconv
  import dipy.reconst.base
  from dipy.io.image import load_nifti_data
  from dipy.reconst.shm import descoteaux07_legacy_msg
  from dipy.testing.decorators import set_random_number_generator
label_desc: Use image node_id 1 for calling a global function with example usage: test_coeff_of_determination(rng) without return types