def get_proficiency_notification_session(self, proficiency_receiver, proxy):
raise Unimplemented()<EOL>
Gets the ``OsidSession`` associated with the proficiency notification service.

        :param proficiency_receiver: the notification callback
        :type proficiency_receiver: ``osid.learning.ProficiencyReceiver``
        :param proxy: a proxy
        :type proxy: ``osid.proxy.Proxy``
        :return: a ``ProficiencyNotificationSession``
        :rtype: ``osid.learning.ProficiencyNotificationSession``
        :raise: ``NullArgument`` -- ``proficiency_receiver`` or ``proxy`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``Unimplemented`` -- ``supports_proficiency_notification()`` is ``false``

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