@staticmethod<EOL><INDENT>def diff_in_days(start, end):<DEDENT>
diff = date(end.year, end.month, end.day) - date(start.year, start.month, start.day)<EOL>return float(diff.days)<EOL>
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