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

        let uri = match parts.next() {

            Some(s) => s,

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

        let offset = match parts.next() {

            Some(s) => s

                .parse::<Offset>()

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

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

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

        Ok((Request::ReadPicture(uri.to_string(), offset), ""))

    }

    fn parse_response(

        parts: ResponseAttributes<'_>,

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

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

        if parts.is_empty() {

            return Ok(None);

        }

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

        let binary = get_property!(parts, "binary", Binary).into();

        let mimetype = get_optional_property!(parts, "mimetype", Text).map(|s| s.to_string());

        Ok(Some(ReadPictureResponse {

            size,

            binary,

            mimetype,

        }))

    }