code: def diff_in_days(start, end):
          
  
          diff = from_ymd_to_excel(*end.date)-from_ymd_to_excel(*start.date)
          return float(diff)
docs: calculate difference between given dates in days
  
          :param BaseDateTuple start: state date
          :param BaseDateTuple end: end date
          :return float: difference between end date and start date in days