def _get_class(class_name: str) -> types.ModuleType:
        """
        Get a class module from its name.

        :param class_name: Full name of a class.
        :return: The class `module`.
        """
        sub_mods = class_name.split(".")
        module_ = __import__(".".join(sub_mods[:-1]), fromlist=sub_mods[-1])
        class_module = getattr(module_, sub_mods[-1])

        return class_module

        Get a class module from its name.

        :param class_name: Full name of a class.
        :return: The class `module`.
        
art/attacks/evasion/targeted_universal_perturbation.py