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

        let time_raw = match parts.next() {

            Some(t) => t,

            None => return Err(RequestParserError::UnexpectedEOF),

        let (mode, time) = match time_raw {

            t if t.starts_with('+') => (

                SeekMode::Relative,

                t[1..]

                    .parse::<TimeWithFractions>()

                    .map_err(|_| RequestParserError::SyntaxError(0, t.to_owned()))?,

            t if t.starts_with('-') => (

                SeekMode::Relative,

                -t[1..]

                    .parse::<TimeWithFractions>()

                    .map_err(|_| RequestParserError::SyntaxError(0, t.to_owned()))?,

            t => (

                SeekMode::Absolute,

                t.parse::<TimeWithFractions>()

                    .map_err(|_| RequestParserError::SyntaxError(0, t.to_owned()))?,

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

        Ok((Request::SeekCur(mode, time), ""))

    }

    fn parse_response(

        parts: ResponseAttributes<'_>,

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

        debug_assert!(parts.is_empty());

        Ok(())

    }