lengthSync method
The length of all files in this Directory provided synchronously.
Throws a FileSystemException if the operation fails.
Implementation
int lengthSync({
  bool followLinks = true,
}) {
  var len = 0;
  for (final item in listSync(recursive: true, followLinks: followLinks)) {
    if (item is! File) continue;
    len += item.lengthSync();
  }
  return len;
}