title: Django - get queryset with id's not in set of values
body: <p>According to doc - 
  <a href="https://docs.djangoproject.com/en/dev/topics/db/queries/#the-pk-lookup-shortcut" rel="nofollow noreferrer">https://docs.djangoproject.com/en/dev/topics/db/queries/#the-pk-lookup-shortcut</a> - 
  I can get set of objects with specified in list ids. Is there any short way to get another set of objects, with id's not in the specified list. Blog.objects.filter(pk__not_in=[1,4,7]) - did not work for me. <em>PS: is there any annotation of possible expresissions for filtering querysets, of making own short expressions?</em></p>