fn scan_backend<R, E>(
reader: SerializedFileReader<R>,
send: &Sender<Result<Vec<E>>>,
path: &Path,
pb: ProgressBar,
) -> Result<()>
fn scan_backend<R, E>(
reader: SerializedFileReader<R>,
send: &Sender<Result<Vec<E>>>,
path: &Path,
pb: ProgressBar,
) -> Result<()>