code: def test_H12(self):
      h = haralick.Haralick(gray, labels, 0, 1, nlevels=4)
      self.assertAlmostEqual(h.H12()[0], -0.5285, 4)
  
imports: import unittest
  import centrosome.haralick
  import numpy
label_desc: Use image node_id 16 for calling the TestHaralick obj's underlying member method code with example usage: obj.test_H12() without return types