/// <summary>
 /// Returns the previous working day (Mon-Fri, not public holiday)
 /// before the specified date (or the same date)
 /// </summary>
 /// <param name="dt">The date you wish to check</param>
 /// <returns>A date that is a working day</returns>
 public DateTime PreviousWorkingDay(DateTime dt)
 {
     return(HolidayCalculator.PreviousWorkingDay(this, dt));
 }