def get_score_system(self):
<EOL>if not bool(self._my_map['<STR_LIT>']):<EOL><INDENT>raise errors.IllegalState('<STR_LIT>')<EOL><DEDENT>mgr = self._get_provider_manager('<STR_LIT>')<EOL>if not mgr.supports_grade_system_lookup():<EOL><INDENT>raise errors.OperationFailed('<STR_LIT>')<EOL><DEDENT>lookup_session = mgr.get_grade_system_lookup_session(proxy=getattr(self, "<STR_LIT>", None))<EOL>lookup_session.use_federated_gradebook_view()<EOL>osid_object = lookup_session.get_grade_system(self.get_score_system_id())<EOL>return osid_object<EOL>
Gets the grade system for the score.

        return: (osid.grading.GradeSystem) - the grade system
        raise:  IllegalState - ``is_scored()`` is ``false``
        raise:  OperationFailed - unable to complete request
        *compliance: mandatory -- This method must be implemented.*