code: def business_days(start, stop):
      
      dates=rrule.rruleset()
      # Get dates between start/stop (which are inclusive)
      dates.rrule(rrule.rrule(rrule.DAILY, dtstart=start, until=stop))
      # Exclude Sat/Sun 
      dates.exrule(rrule.rrule(rrule.DAILY, byweekday=(rrule.SA, rrule.SU), dtstart=start)) 
      return dates.count()
docs: Return business days between two inclusive dates - ignoring public holidays.
      
      Note that start must be less than stop or else 0 is returned.
      
      @param start: Start date
      @param stop: Stop date
      @return int