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

        let uri = parts

            .next()

            .map(|s| {

                s.parse()

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

            })

            .transpose()?;

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

        Ok((Request::ListFiles(uri), ""))

    }

    fn parse_response(

        parts: ResponseAttributes<'_>,

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

        unimplemented!()