@abc.abstractmethod<EOL><INDENT>def get_objective_bank_ids_by_objective(self, objective_id):<DEDENT>
return<EOL>
Gets the list of ``ObjectiveBank``  ``Ids`` mapped to an ``Objective``.

        :param objective_id: ``Id`` of an ``Objective``
        :type objective_id: ``osid.id.Id``
        :return: list of objective bank ``Ids``
        :rtype: ``osid.id.IdList``
        :raise: ``NotFound`` -- ``objective_id`` is not found
        :raise: ``NullArgument`` -- ``objective_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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