code: function (root, options, watchCallback, initCallback) {
        if (!watchCallback) {
          watchCallback = options;
          options = {}
        }
        lessWatchCompilerUtilsModule.walk(root, options, function (err, files) {
            if (err) throw err;
            lessWatchCompilerUtilsModule.fileWatcher(root, files, options, filelist, fileimportlist, watchCallback);
            for (var i in files) {
              lessWatchCompilerUtilsModule.fileWatcher(i, files, options, filelist, fileimportlist, watchCallback);
            }
            watchCallback(files, null, null, fileimportlist);
          },
          initCallback);
      }
docs: Setup fs.watchFile() for each file.