def selenol_params(**kwargs):
    """Decorate request parameters to transform them into Selenol objects."""
    def params_decorator(func):
        """Param decorator.

        :param f: Function to decorate, typically on_request.
        """
        def service_function_wrapper(service, message):
            """Wrap function call.

            :param service: SelenolService object.
            :param message: SelenolMessage request.
            """
            params = {k: f(service, message) for k, f in kwargs.items()}
            return func(service, **params)
        return service_function_wrapper
    return params_decorator
Decorate request parameters to transform them into Selenol objects.