@abc.abstractmethod<EOL><INDENT>def register_for_changed_objective_bank_hierarchy_for_ancestors(self, objective_bank_id):<DEDENT>
pass<EOL>
Registers for notification of an updated objective bank hierarchy structure.

        ``ObjectiveBankReceiver.changedChildOfObjectiveBanks()`` is
        invoked when the specified node or any of its ancestors
        experiences a change in its children.

        :param objective_bank_id: the ``Id`` of the ``ObjectiveBank`` node to monitor
        :type objective_bank_id: ``osid.id.Id``
        :raise: ``NullArgument`` -- ``objective_bank_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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