function CDate(calendar, year, month, day) {
        this._calendar = calendar;
        this._year = year;
        this._month = month;
        this._day = day;
        if (this._calendar._validateLevel === 0 && !this._calendar.isValid(this._year, this._month, this._day)) {
          throw (_exports.local.invalidDate || _exports.regionalOptions[""].invalidDate).replace(/\{0\}/, this._calendar.local.name);
        }
      }
Digit substitution function for localising Chinese style numbers via the Calendar digits option.
            @member Calendars
            @param digits {string[]} The substitute digits, for 0 through 9.
            @param powers {string[]} The characters denoting powers of 10, i.e. 1, 10, 100, 1000.
            @return {function} The substitution function.