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

        let playlist_name = parts

            .next()

            .ok_or(RequestParserError::UnexpectedEOF)?

            .to_string();

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

        Ok((Request::PlaylistLength(playlist_name), ""))

    }

    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(PlaylistLengthResponse { songs, playtime })

    }