@abc.abstractmethod<EOL><INDENT>def get_date_time_value(self):<DEDENT>
return<EOL>
Gets the value if it is a ``DateTime``.

        :return: the value
        :rtype: ``osid.calendaring.DateTime``
        :raise: ``IllegalState`` -- ``Parameter.getSyntax() != DATETIME``

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