code: def test_mad_center(self):
      n = scale.mad(self.X, center=0)
      assert_equal(n.shape, (10,))
      with pytest.raises(TypeError):
          scale.mad(self.X, center=None)
      assert_almost_equal(
          scale.mad(self.X, center=1),
          np.median(np.abs(self.X - 1), axis=0) / Gaussian.ppf(3 / 4.0),
          DECIMAL,
      )
  
imports: import numpy
  from numpy.random import standard_normal
  from numpy.testing import assert_almost_equal, assert_equal
  import pytest
  from scipy.stats import norm
  import statsmodels.api
  import statsmodels.robust.scale
  from statsmodels.robust.scale import mad
label_desc: Use image node_id 4 for calling the TestMad obj's underlying member method code with example usage: obj.test_mad_center() without return types