code: def test_logprob(self):
      y = self._build_placeholder([1.0, 2.5, 4.3, 6.1, 7.8])
  
      ssm = LocalLinearTrendStateSpaceModel(
          num_timesteps=5,
          level_scale=0.5,
          slope_scale=0.5,
          initial_state_prior=mvn_diag.MultivariateNormalDiag(
              scale_diag=self._build_placeholder([1.0, 1.0])
          ),
      )
  
      lp = ssm.log_prob(y[..., np.newaxis])
      expected_lp = -5.801624298095703
      self.assertAllClose(self.evaluate(lp), expected_lp)
  
imports: import numpy
  import tensorflow.compat.v1
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import mvn_diag
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.sts.components.local_linear_trend import LocalLinearTrendStateSpaceModel
label_desc: Use image node_id 1 for calling the _LocalLinearTrendStateSpaceModelTest obj's underlying member method code with example usage: obj.test_logprob() without return types