@abc.abstractmethod<EOL><INDENT>def get_function_notification_session(self, function_receiver):<DEDENT>
return<EOL>
Gets the notification session for notifications pertaining to function changes.

        :param function_receiver: the function receiver
        :type function_receiver: ``osid.authorization.FunctionReceiver``
        :return: a ``FunctionNotificationSession``
        :rtype: ``osid.authorization.FunctionNotificationSession``
        :raise: ``NullArgument`` -- ``function_receiver`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``Unimplemented`` -- ``supports_function_notification()`` is ``false``

        *compliance: optional -- This method must be implemented if
        ``supports_function_notification()`` is ``true``.*