code: def test_dist(self):
      model = GaussianMLPModel(output_dim=1)
      dist = model.build(self.input_var).dist
      assert isinstance(dist, tfp.distributions.MultivariateNormalDiag)
  
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 2 for calling the TestGaussianMLPModel obj's underlying member method code with example usage: obj.test_dist() without return types