code: function(year, month, day) {
          this._validate(year, month, day,
              _exports.local.invalidDate || _exports.regionalOptions[''].invalidDate);
          return {};
      }
docs: Retrieve additional information about a date.
  @memberof BaseCalendar
  @param year {CDate|number} The date to examine or the year to examine.
  @param [month] {number} The month to examine.
  @param [day] {number} The day to examine.
  @return {object} Additional information - contents depends on calendar.
  @throws Error if an invalid date or a different calendar used.