Incremental flash backup tool

I recently decided that I would back up my documents to a high capacity flash disk. Thus I wrote a backup tool.
Features:

• Dead simple. Something you'd write in an hour, so it won't mess you up by having volumes of code, weird interfaces, complicated man pages, or obscure back up formats.
  
• The flash disk is a mirrored filesystem, so no special tools are required to read the backup.
  
• The existing backed-up filesystem is updated if the backup command is re-issued.
  
• Specified directories are recursively copied; hidden files are not copied. Thus one can flag large files that should not be backed up: make them hidden.
  
• Eventually needs support for checksums, but I'm not too worried at the moment.
  

The program is public domain. Download and run it. Copy its example backup command line into a shell script. In my case, I use something similar to:

  % python backup.py D:\ D:\Documents D:\Code G:\Backup

(Source Code)