code: function watcher(manifest)
  {
    return function(file)
    {
      return function(event)
      {
        if (event == 'change')
        {
          fs.stat(file, function(err, stat)
          {
            if (err) return; // do nothing at this point
  
            var mtime = stat.mtime.getTime();
  
            if (cache[manifest].version < mtime) cache[manifest].version = mtime;
          });
        }
  
        // TODO: add support for rename, maybe
      };
    }
  }
docs: generates version watcher callback going total inception