code: function(date) {
        if (_.isDate(date)) {
          this._date = date.toSerialNumber();
        } else if (_.isNumber(date)) {
          this._date = date;
        } else {
          throw new CError('wrong date type').log();
        }
      }
docs: Set the date
  @param {Date/Integer} date The date as date or number of milliseconds. The date is anyhow saved as integer.