code: def test_check_weights_none(n_matrices):
      w = check_weights(None, n_matrices)
      assert np.sum(w) == pytest.approx(1.0, abs=1e-10)
  
imports: import numpy
  import pytest
  from pyriemann.utils.utils import check_weights
label_desc: Use image node_id 1 for calling a global function with example usage: test_check_weights_none(n_matrices) without return types