code: def test_mismatched_observation_size_error(self):
      seed = test_util.test_seed(sampler_type="stateless")
      ssm1 = self._dummy_model(observation_size=1)
      ssm2 = self._dummy_model(observation_size=2)
  
      with self.assertRaisesWithPredicateMatch(Exception, ""):
          # In the static case, the constructor should raise an exception.
          additive_ssm = AdditiveStateSpaceModel(
              component_ssms=[ssm1, ssm2]
          )
  
          # In the dynamic case, the exception is raised at runtime.
          _ = self.evaluate(additive_ssm.sample(seed=seed))
  
imports: from absl.testing import parameterized
  import numpy
  import tensorflow.compat.v1
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import linear_gaussian_ssm
  from tensorflow_probability.python.distributions import mvn_diag
  from tensorflow_probability.python.internal import tensorshape_util
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.sts.components.local_linear_trend import LocalLinearTrendStateSpaceModel
  from tensorflow_probability.python.sts.components.sum import AdditiveStateSpaceModel
label_desc: Use image node_id 9 for calling the _AdditiveStateSpaceModelTest obj's underlying member method code with example usage: obj.test_mismatched_observation_size_error() without return types