@abc.abstractmethod<EOL><INDENT>def get_grade(self):<DEDENT>
return<EOL>
Gets a grade for the assessment.

        :return: the grade
        :rtype: ``osid.grading.Grade``
        :raise: ``IllegalState`` -- ``is_graded()`` is ``false``
        :raise: ``OperationFailed`` -- unable to complete request

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