code: def test_distance_mahalanobis(rndstate, complex_valued):
      n_channels, n_times = 3, 100
      X = rndstate.randn(n_channels, n_times)
      if complex_valued:
          X = X + 1j * rndstate.randn(n_channels, n_times)
      d = distance_mahalanobis(X, np.cov(X))
      assert d.shape == (n_times,)
      assert np.all(np.isreal(d))
  
imports: from conftest import get_distances
  import numpy
  from numpy.testing import assert_array_almost_equal
  from scipy.spatial.distance import euclidean, mahalanobis
  import pytest
  from pytest import approx
  from pyriemann.utils.distance import distance_euclid, distance_harmonic, distance_kullback, distance_kullback_right, distance_kullback_sym, distance_logdet, distance_logeuclid, distance_riemann, distance_wasserstein, distance, pairwise_distance, distance_mahalanobis
  from pyriemann.utils.base import logm
  from pyriemann.utils.geodesic import geodesic
  from pyriemann.utils.test import is_sym
label_desc: Use image node_id 20 for calling a global function with example usage: test_distance_mahalanobis(rndstate, complex_valued) without return types