def opt_without_module(self, option):
        """
        Fake the lack of the specified modules, separated with commas.
        """
        self["without-module"] = option
        for module in option.split(","):
            if module in sys.modules:
                warnings.warn("Module '%s' already imported, "
                              "disabling anyway." % (module,),
                              category=RuntimeWarning)
            sys.modules[module] = None

        Fake the lack of the specified modules, separated with commas.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/scripts/trial.py