code: function (data, fragmentKey, cachePath, callback) {
      debug('  write content in file system');
      var basePath =  path.dirname(fragmentKey);
      if (basePath){
        mkdirp.sync(cachePath + '/' + basePath);
      }
      fs.writeFile(cachePath + '/' + fragmentKey, data, function (err) {
        if (err) {
          callback(err);
        } else {
          callback(null, data);
        }
      });
    }
docs: Dump remote content in file system
  @param data Remote content data
  @param fragmentKey Remote content key
  @param cachePath Temp FS cache directory
  @param callback Method to call when file is written