code: public void reset() {
      this.formatMode = null;
      this.roundMode = NumberRoundMode.ROUND;
      this.grouping = null;
      this.minimumIntegerDigits = null;
      this.maximumFractionDigits = null;
      this.minimumFractionDigits = null;
      this.maximumSignificantDigits = null;
      this.minimumSignificantDigits = null;
    }
docs: Reset the options to their defaults.