def get_assessment_notification_session(self, assessment_receiver=None, proxy=None):
if proxy is None:<EOL><INDENT>raise NullArgument()<EOL><DEDENT>raise Unimplemented()<EOL>
Gets the notification session for notifications pertaining to assessment changes.

        arg:    assessment_receiver
                (osid.assessment.AssessmentReceiver): the assessment
                receiver interface
        arg:    proxy (osid.proxy.Proxy): a proxy
        return: (osid.assessment.AssessmentNotificationSession) - an
                ``AssessmentNotificationSession``
        raise:  NullArgument - ``assessment_receiver`` or ``proxy`` is
                ``null``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_assessment_notification()``
                is ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_assessment_notification()`` is ``true``.*