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

        let filter = parse_filter(&mut parts)?;

        let group = if let Some("group") = parts.next() {

            let group = parts.next().ok_or(RequestParserError::UnexpectedEOF)?;

                group

                    .parse()

                    .map_err(|_| RequestParserError::SyntaxError(1, group.to_owned()))?,

            None

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

        Ok((Request::Count(filter, group), ""))

    }

    fn parse_response(

        parts: ResponseAttributes<'_>,

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

        let parts: HashMap<_, _> = parts.into();

        let songs = get_and_parse_property!(parts, "songs", Text);

        let playtime = get_and_parse_property!(parts, "playtime", Text);

        Ok(CountResponse { songs, playtime })

    }