def get_objective_bank_notification_session(self, objective_bank_receiver=None):
raise Unimplemented()<EOL>
Gets the notification session for notifications pertaining to objective bank service changes.

        arg:    objective_bank_receiver
                (osid.learning.ObjectiveBankReceiver): the objective
                bank receiver
        return: (osid.learning.ObjectiveBankNotificationSession) - an
                ``ObjectiveBankNotificationSession``
        raise:  NullArgument - ``objective_bank_receiver`` is ``null``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_objective_bank_notification()
                is false``
        *compliance: optional -- This method must be implemented if
        ``supports_objective_bank_notification()`` is true.*