svoid gzip2xz(S gzInFile, S xzOutFile) {
  gzip2xz(newFile(gzInFile), newFile(xzOutFile));
}

static File gzip2xz(File gzInFile) {
  File xzOutFile = replaceExtension(gzInFile, ".gz", ".xz");
  ret gzip2xz(gzInFile, xzOutFile);
}

static File gzip2xz(File gzInFile, File xzOutFile) {
  printFileInfo("Converting to .xz", gzInFile);
  long time = sysNow();
  copyStreamAndCloseAll(
    gzipInputStream(gzInFile),
    xzOutputStream(xzOutFile));
  printFileInfo("Converted in " + renderElapsedTimePleasantly_100ms(sysNow()-time), xzOutFile);
  ret xzOutFile;
}