code: def diff_in_days(start, end):
          
          diff = date(end.year, end.month, end.day) - date(start.year, start.month, start.day)
          return float(diff.days)
docs: calculate difference between given dates in days
  
          :param BaseDateDatetimeDate start: state date
          :param BaseDateDatetimeDate end: end date
          :return float: difference between end date and start date in days