code: function allowRetry(err) {
      var allowRetry = false;
      var isTimeError = false;
      var serverDate = (err.headers && (err.headers.date || err.headers.Date)) || '';
      try {
          var errorCode = err.error.Code;
          var errorMessage = err.error.Message;
          if (errorCode === 'RequestTimeTooSkewed' ||
              (errorCode === 'AccessDenied' && errorMessage === 'Request has expired')) {
              isTimeError = true;
          }
      } catch (e) {
      }
      if (err) {
          if (isTimeError && serverDate) {
              var serverTime = Date.parse(serverDate);
              if (this.options.CorrectClockSkew && Math.abs(util.getSkewTime(this.options.SystemClockOffset) - serverTime) >= 30000) {
                  console.error('error: Local time is too skewed.');
                  this.options.SystemClockOffset = serverTime - Date.now();
                  allowRetry = true;
              }
          } else if (Math.round(err.statusCode / 100) === 5) {
              allowRetry = true;
          }
      }
      return allowRetry;
  }
docs: 调整时间偏差