code: function storeDirectory(file) {
      var directory = file.fullParentDir;
      if (!watched_directories[directory]) {
        fs.stat(directory, function(err, stats) {
          if (err) {
            watched_directories[directory] = (new Date).getTime();
          } else {
            watched_directories[directory] = (new Date(stats.mtime)).getTime();
          }
        });
      }
    }
docs: Sets up a store of the folders being watched and saves the last modification timestamp for it