code: func (h holidaysUSNational) fixWeekend(in time.Time) time.Time {
  	switch in.Weekday() {
  	case time.Saturday:
  		return in.Add(-1 * 24 * time.Hour)
  	case time.Sunday:
  		return in.Add(1 * 24 * time.Hour)
  	default:
  		return in
  	}
  }
docs: // If a holiday falls on a Saturday it is celebrated the preceding Friday;
  // if a holiday falls on a Sunday it is celebrated the following Monday.