code: def test_median_diff(self):
      np.testing.assert_almost_equal(median_diff(const0), 0.0)
      np.testing.assert_almost_equal(median_diff(const1), 0.0)
      np.testing.assert_almost_equal(median_diff(constNeg), 0.0)
      np.testing.assert_almost_equal(median_diff(constF), 0.0)
      np.testing.assert_almost_equal(median_diff(lin), 1.0)
      np.testing.assert_almost_equal(
          median_diff(lin0), 1.0526315789473684, decimal=5
      )
      np.testing.assert_almost_equal(
          median_diff(wave), -0.0004934396342684, decimal=5
      )
      np.testing.assert_almost_equal(
          median_diff(offsetWave), -0.0004934396342681779, decimal=5
      )
      np.testing.assert_almost_equal(
          median_diff(noiseWave), -0.004174819648320949, decimal=5
      )
  
imports: import unittest
  import numpy
  from tsfel.feature_extraction.features import *
label_desc: Use image node_id 23 for calling the TestFeatures obj's underlying member method code with example usage: obj.test_median_diff() without return types