svoid test_BackupThinner() {
  new BackupThinner bt;
  bt.allFiles(ll(
    newFile("concepts.structure.gz.backup20240518-21"),
    newFile("concepts.structure.gz.backup20240518-19"),
    newFile("concepts.structure.gz.backup20240401-10")));
  bt.timeZone(germanTimeZone());
  bt.currentTime(timestampFromYMDHM(2024, 5, 18, 22, 0, bt.timeZone()));
  bt.scan();
  pnl(bt.deletableFiles);
}