code: def test_normalize(self):
      phi = self.phi1.copy()
      phi.normalize()
      self.assertEqual(self.phi1.variables, phi.variables)
      np_test.assert_array_equal(self.phi1.mean, phi.mean)
      np_test.assert_array_equal(self.phi1.covariance, phi.covariance)
      self.assertEqual(
          self.phi1._precision_matrix, phi._precision_matrix
      )
  
      phi = self.phi1.normalize(inplace=False)
      self.assertEqual(self.phi1.variables, phi.variables)
      np_test.assert_array_equal(self.phi1.mean, phi.mean)
      np_test.assert_array_equal(self.phi1.covariance, phi.covariance)
      self.assertEqual(
          self.phi1._precision_matrix, phi._precision_matrix
      )
  
imports: import unittest
  import numpy
  import numpy.testing
  from pgmpy.factors.distributions import GaussianDistribution
label_desc: Use image node_id 7 for calling the TestJGDMethods obj's underlying member method code with example usage: obj.test_normalize() without return types