code: def opt_dep(request):
      """Optional dependency fixture.
      Tests that use this fixture must be run with the --opt-dep option via terminal. If not they will skip. This fixture
      is used in CI to indicate the optional dependencies installed in the tox environments the tests are run in. See
      setup.cfg and .github/workflows/ci.yml for more details.
      """
      opt_dep_value = request.config.option.opt_dep
      if opt_dep_value is None:
          pytest.skip()
      return opt_dep_value
  
label_desc: Use image node_id 2 for calling a global function with example usage: opt_dep(request) and returns: opt_dep_value