code: function(year) {
          var date = this._validate(year, this.minMonth, this.minDay,
              _exports.local.invalidYear || _exports.regionalOptions[''].invalidYear);
          return (date.year() < 0 ? '-' : '') + pad(Math.abs(date.year()), 4)
      }
docs: Format the year, if not a simple sequential number
  @memberof BaseCalendar
  @param year {CDate|number} The date to format or the year to format.
  @return {string} The formatted year.
  @throws Error if an invalid year or a different calendar used.