@abc.abstractmethod<EOL><INDENT>def get_num_days_for_month(self, year, month):<DEDENT>
return<EOL>
Gets the number of days in the given month.

        :param year: a year
        :type year: ``integer``
        :param month: a ``DateTime`` month code
        :type month: ``cardinal``
        :return: the number of days
        :rtype: ``cardinal``
        :raise: ``IllegalState`` -- ``year`` is greater than ``get_last_year_before_common_era()`` and less then ``get_first_year_in_common_era()`` , or ``month`` is greater than ``get_months_for_year(year)``
        :raise: ``OperationFailed`` -- unable to complete request

        *compliance: mandatory -- This method must be implemented.*