code: def test_gradient(self):
      grad, log = self.test_gradient.get_gradient_log_pdf()
      np.testing.assert_almost_equal(
          grad,
          np.array([0.05436475, 0.49454937, 0.75465073, 0.77837868]),
      )
      np.testing.assert_almost_equal(log, -3.21046521505)
  
imports: import unittest
  import numpy
  from pgmpy.factors.distributions import GaussianDistribution
  from pgmpy.sampling import LeapFrog, ModifiedEuler, GradLogPDFGaussian
label_desc: Use image node_id 3 for calling the TestGradLogPDFGaussian obj's underlying member method code with example usage: obj.test_gradient() without return types