code: function isHoliday(db, date, callback) {
  
    // Check cache for is holiday
    let cacheKey = db.id + "-" + date;
    let cache = cache_isHolidayByDate.get(cacheKey);
    if ( cache !== null ) {
      return callback(null, cache);
    }
  
    // Get matching holiday
    let select = "SELECT date, holiday_name, peak, service_info " +
      "FROM rt_holidays WHERE date=" + date;
  
    // Query the database
    db.get(select, function(err, result) {
  
      // Database Query Error
      if ( err ) {
        return callback(err);
      }
  
      // Add result to cache
      cache_isHolidayByDate.put(cacheKey, result !== undefined);
  
      // Return if holiday is found with callback
      return callback(null, result !== undefined);
  
    });
  
  }
docs: Check if the specified date is a Holiday
  
  @param {RightTrackDB} db The Right Track DB to query
  @param {int} date The date to check (yyyymmdd)
  @param {function} callback Callback function
  @param {Error} callback.error Database Query Error
  @param {boolean} [callback.isHoliday] True if the specified date is a Holiday