code: function write(callback) {
      function doWrite(modules, cacheKey, contentsKey, callback) {
        async.each(modules, function(module, callback) {
          module[cacheKey] = uuid.v1();
  
          fs.writeFile(path.resolve(directory, module[cacheKey]), module[contentsKey], callback);
        }, callback);
      }
  
      async.parallel([
        doWrite.bind(doWrite, _.filter(modulesArray, {cached: null}), 'cached', 'contents'),// 保存模块
        doWrite.bind(doWrite, emitModulesArray, 'emitCached', 'srcContents')// 保存创建的模块
      ], callback);
    }
docs: 保存编译结果