fn parse_request(mut parts: SplitWhitespace<'_>) -> RequestParserResult<'_> {

        let result = parts

            .next()

            .map_or(Ok((Request::Idle(None), "")), |subsystems| {

                let subsystems = subsystems

                    .split(',')

                    .map(|subsystem| SubSystem::from_str(subsystem).unwrap())

                    .collect();

                Ok((Request::Idle(Some(subsystems)), ""))

            });

        debug_assert!(parts.next().is_none());

        result

    }

    fn parse_response(

        parts: ResponseAttributes<'_>,

    ) -> Result<Self::Response, ResponseParserError> {

        debug_assert!(parts.is_empty());

        Ok(())

    }