fn list_filesystems<N: Into<PathBuf>>(&self, pool: N) -> Result<impl Iterator<Item = PathBuf> {
        let mut z = self.zfs_mute();
        z.args(&["list", "-t", "filesystem", "-o", "name", "-Hpr"]);
        z.arg(pool.into().as_os_str());
        debug!(self.logger, "executing"; "cmd" => format_args!("{:?}", z));
        let out = z.output()?;
        if out.status.success() {
            let stdout = String::from_utf8_lossy(&out.stdout);
            ZfsParser::parse(Rule::datasets, &stdout)
                .map(|mut pairs| {
                    pairs.next().unwrap().into_inner()
                        .map(|pair| {
                            debug_assert_eq!(Rule::dataset_name, pair.as_rule());
                            PathBuf::from(pair.as_str())
                        })
                })
                .map_err(|_| Error::UnknownSoFar(String::from(stdout)))
        } else {
            Err(Error::from_stderr(&out.stderr))
        }