@abc.abstractmethod<EOL><INDENT>def get_level_id(self):<DEDENT>
return<EOL>
Gets the proficiency level expressed as a grade.

        :return: the grade ``Id``
        :rtype: ``osid.id.Id``
        :raise: ``IllegalState`` -- ``has_level()`` is ``false``

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