_Og hSrSSKJr SSKrSSKrSSKJr \R"S5r SSjr SSjr g) z!A collection of useful utilities.N)compatz^(-?(?:[1-9][0-9]*)?[0-9]{4})-(1[0-2]|0[1-9])-(3[0-1]|0[1-9]|[1-2][0-9])(T(2[0-3]|[0-1][0-9]):([0-5][0-9]):([0-5][0-9])(\.[0-9]+)?(Z|[+-](?:2[0-3]|[0-1][0-9]):[0-5][0-9])?)?$cRUcU(ag[S5e[U[R5(aUR5S-$[U[R 5(a*[ RU5(d[SU-5eU$[S[U5-5e)aFunction to check the conformance of timestamps passed by users. This will check that a string is a valid format and allow users to pass a datetime object which we will then convert to a proper ISO8601 date-time string. :param timestamp: string to be validated or datetime object to be converted. :param bool allow_none: whether or not to allow timestamp to be None. Default: ``True`` :returns: valid ISO8601 string :rtype: str :raises: ValueError NzTimestamp value cannot be NoneZzr1s5')  :: "NJ#r