[FIX] url fix with regex.

annotations/urls.py

@@ -5,6 +5,6 @@ from annotations import views
 urlpatterns = patterns('',
     url(r'^document/(?P<doc_id>[0-9]+)$', views.Document.as_view()), # document view
     url(r'^corpus/(?P<corpus_id>[0-9]+)/document/(?P<doc_id>[0-9]+)$', views.NgramList.as_view()), # the list associated with an ngram
-    url(r'^lists/(?P<list_id>[0-9]+)/ngrams/(?P<ngram_ids>([0-9]+(\+[0-9]+)*)$', views.NgramEdit.as_view()), #
+    url(r'^lists/(?P<list_id>[0-9]+)/ngrams/(?P<ngram_ids>[0-9]+\+*[0-9]*)$', views.NgramEdit.as_view()), #
     url(r'^lists/(?P<list_id>[0-9]+)/ngrams/create$', views.NgramCreate.as_view()), #
 )