Gets the calculated entry this entry overrides.

        return: (osid.grading.GradeEntry) - the calculated entry
        raise:  IllegalState - ``overrides_calculated_entry()`` is
                ``false``
        raise:  OperationFailed - unable to complete request
        *compliance: mandatory -- This method must be implemented.*

def get_overridden_calculated_entry(self):
        """Gets the calculated entry this entry overrides.

        return: (osid.grading.GradeEntry) - the calculated entry
        raise:  IllegalState - ``overrides_calculated_entry()`` is
                ``false``
        raise:  OperationFailed - unable to complete request
        *compliance: mandatory -- This method must be implemented.*

        """
        # Implemented from template for osid.resource.Resource.get_avatar_template
        if not bool(self._my_map['overriddenCalculatedEntryId']):
            raise errors.IllegalState('this GradeEntry has no overridden_calculated_entry')
        mgr = self._get_provider_manager('GRADING')
        if not mgr.supports_grade_entry_lookup():
            raise errors.OperationFailed('Grading does not support GradeEntry lookup')
        lookup_session = mgr.get_grade_entry_lookup_session(proxy=getattr(self, "_proxy", None))
        lookup_session.use_federated_gradebook_view()
        osid_object = lookup_session.get_grade_entry(self.get_overridden_calculated_entry_id())
        return osid_object