How to use the utility.base64encode function in utility

exports.uploadToken = function uploadToken(options) {
  options = options || {};
  options.scope = options.scope || this.options.bucket;
  options.deadline = options.deadline || (utility.timestamp() + 3600);
  var flags = options;
  // 步骤2：将 Flags 进行安全编码
  var encodedFlags = utility.base64encode(JSON.stringify(flags), true);

  // 步骤3：将编码后的元数据混入私钥进行签名
  // 步骤4：将签名摘要值进行安全编码
  var encodedSign = this.signData(encodedFlags);

  // 步骤5：连接各字符串，生成上传授权凭证
  return this.options.accessKey + ':' + encodedSign + ':' + encodedFlags;
};

exports.fetch = function (url, key, callback) {
  var encodedURL = utility.base64encode(url);
  var pathname = '/fetch/' + encodedURL + '/to/' + this.encodeEntryURI(key);
  this._rsAction(pathname, callback, 'http://iovip.qbox.me');
};

exports.encodeEntryURI = function (key) {
  key = this.resourceKey(key);
  return utility.base64encode(this.options.bucket + ':' + key, true);
};

exports.getGithubBasicAuth = function (argument) {
  return config.githubToken
    ? 'Basic ' + utility.base64encode(util.format('%s:x-oauth-basic', config.githubToken))
    : '';
};

function rc4Encrypt(data) {
    return encodeHex(rc4(utility.base64encode(data), KEY));
}

exports.request = function request(url, args) {
  assert(url, 'url required');
  args = args || {};

  var input = utility.base64encode(JSON.stringify({
    url: url,
    args: args
  }));
  var requestPath = path.join(__dirname, './request.js');

  var cmd = process.execPath;
  var _args = [requestPath, input];
  var res = cp.spawnSync(cmd, _args, {
    timeout: (args.timeout || 3000) + 1000
  });

  if (res.error) {
    res.error.url = url;
    res.error.args = args;
    throw res.error;
  }