code: def test_H3(self):
      h = haralick.Haralick(gray, labels, 0, 1, nlevels=4)
      self.assertAlmostEqual(h.mux[0], 2.0833, 4)
      self.assertAlmostEqual(h.muy[0], 2.5000, 4)
      self.assertAlmostEqual(h.sigmax[0], 1.0375, 4)
      self.assertAlmostEqual(h.sigmay[0], 0.9574, 4)
      self.assertAlmostEqual(h.H3()[0], 0.7970, 4)
  
imports: import unittest
  import centrosome.haralick
  import numpy
label_desc: Use image node_id 7 for calling the TestHaralick obj's underlying member method code with example usage: obj.test_H3() without return types