code: def test_unknown_std_parameterization(self):
      with pytest.raises(ValueError):
          GaussianMLPModel(output_dim=1, std_parameterization="unknown")
  
imports: import pickle
  import numpy
  import pytest
  import tensorflow
  import tensorflow_probability
  from garage.tf.models import GaussianMLPModel
  from tests.fixtures import TfGraphTestCase
label_desc: Use image node_id 17 for calling the TestGaussianMLPModel obj's underlying member method code with example usage: obj.test_unknown_std_parameterization() without return types