def test_moments(self):

        p = Beta([2, 3])
        u = p._message_to_child()
        self.assertAllClose(u[0],
                            special.psi([2,3]) - special.psi(2+3))
        
        pass
Test the moments of beta nodes.
dataset/ETHPy150Open bayespy/bayespy/bayespy/inference/vmp/nodes/tests/test_beta.py/TestBeta.test_moments