code: function _startWatchdog() {
      if (!watcher) {
        var watcherOptions = { persistent: !!options.persistent };
        watcher = fs.watch(folder, watcherOptions, function (event, filename) {
          if (event === 'change' && filename.charAt(0) != '.') {
            // On every change load the changed file. This will trigger notifications for interested
            // subscribers.
            _loadFile(filename);
          }
        });
      }
    }
docs: Start watching directory changes.