formatNumber(number, granularity) {
    return this._formatNumberWithGranularity(number, granularity);
  }
Format number.
@param {number} number
@param {number=} granularity Controls how coarse the displayed value is.
                             If undefined, the number will be displayed as described
                             by the Intl defaults: tinyurl.com/7s67w5x7
@return {string}