code: def _equivalent_likelihoods_fixture(
      request: SubRequest,
  ) -> EquivalentLikelihoods:
      if request.param == "studentt":
          return (
              gpflow.likelihoods.StudentT(
                  scale=Data.g_var**0.5, df=3.0
              ),
              HeteroskedasticTFPConditional(
                  distribution_class=student_t_class_factory(df=3)
              ),
          )
      elif request.param == "gaussian":
          return (
              gpflow.likelihoods.Gaussian(variance=Data.g_var),
              HeteroskedasticTFPConditional(
                  distribution_class=tfp.distributions.Normal
              ),
          )
      assert False, f"Unknown likelihood {request.param}."
  
file_path: GPflow/tests/gpflow/likelihoods/test_heteroskedastic_constant_variance.py
imports: from typing import Tuple, Type
  import numpy
  import pytest
  import tensorflow
  import tensorflow_probability
  from _pytest.fixtures import SubRequest
  from check_shapes import ShapeChecker
  import gpflow
  from gpflow.base import AnyNDArray, TensorType
  from gpflow.likelihoods import HeteroskedasticTFPConditional
label_desc: Use image node_id 2 for calling a global function with example usage: _equivalent_likelihoods_fixture(request) and returns: gpflow,  HeteroskedasticTFPConditional, gpflow,  HeteroskedasticTFPConditional