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

        let range = parts

            .next()

            .map(|range| {

                range

                    .parse()

                    .map_err(|_| RequestParserError::SyntaxError(0, range.to_string()))

            })

            .transpose()?;

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

        Ok((Request::Shuffle(range), ""))

    }

    fn parse_response(

        parts: ResponseAttributes<'_>,

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

        debug_assert!(parts.is_empty());

        Ok(())

    }