code: def test_discrete_obs():
      def model():
          a = pyro.sample("a", dist.Normal(0, 1))
          b = pyro.sample(
              "b", dist.Normal(a[..., None], torch.ones(3)).to_event(1)
          )
          c = pyro.sample(
              "c",
              dist.MultivariateNormal(
                  torch.zeros(3) + a[..., None], torch.eye(3)
              ),
          )
          with pyro.plate("i", 2):
              d = pyro.sample("d", dist.Dirichlet((b + c).exp()))
              pyro.sample(
                  "e",
                  dist.Categorical(logits=d),
                  obs=torch.tensor([0, 0]),
              )
          return a, b, c, d
  
      actual = get_dependencies(model)
      expected = {
          "prior_dependencies": {
              "a": {"a": set()},
              "b": {"a": set(), "b": set()},
              "c": {"a": set(), "c": set()},
              "d": {"b": set(), "c": set(), "d": set()},
              "e": {"d": set(), "e": set()},
          },
          "posterior_dependencies": {
              "a": {"a": set(), "b": set(), "c": set()},
              "b": {"b": set(), "c": set(), "d": set()},
              "c": {"c": set(), "d": set()},
              "d": {"d": set(), "e": set()},
          },
      }
      assert actual == expected
  
imports: import pytest
  import torch
  import pyro
  import pyro.distributions
  from pyro.distributions.testing.fakes import NonreparameterizedNormal
  from pyro.infer.inspect import _deep_merge, get_dependencies, get_model_relations
label_desc: Use image node_id 6 for calling a global function with example usage: test_discrete_obs() and returns: a,  b,  c,  d