Python-сообщество

>>> dt_value = measuring_datetime.objects.latest('dt_value')
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "C:\Python25\Lib\site-packages\django\db\models\manager.py", line 93, in
latest
    return self.get_query_set().latest(*args, **kwargs)
  File "C:\Python25\lib\site-packages\django\db\models\query.py", line 306, in l
atest
    return self._clone(_limit=1, _order_by=('-'+latest_by,)).get()
  File "C:\Python25\lib\site-packages\django\db\models\query.py", line 263, in g
et
    raise self.model.DoesNotExist, "%s matching query does not exist." % self.mo
del._meta.object_name
DoesNotExist: measuring_datetime matching query does not exist.

try :
   dt_value = measuring_datetime.objects.latest('dt_value')
exception DoesNotExist: 
   print "DoesNotExist"
[code]

получаю 
[code]
NameError at /
global name 'DoesNotExist' is not defined
Request Method: 	GET
Request URL: 	http://127.0.0.1:8000/
Exception Type: 	NameError
Exception Value: 	global name 'DoesNotExist' is not defined[/code]
как сделать import для данного exception

try:
    page = Page.objects.get(url='/page_url/')
except Page.DoesNotExist:
    print "What's a funny url for page? :)"

try: measuring_datetime.DoesNotExist