old_contents: from django.conf.urls import url
  from django.contrib import admin
  from api.views import api_root, ChoicesView, QuestionsView, AnswersView, LatestAnswerView
  
  urlpatterns = [
      url(r'^$', api_root),
      url(r'^admin/', admin.site.urls),
      url(r'^questions/(?P<k>[0-9]+)/$',\
          QuestionsView.as_view(), name='questions-get'),
      url(r'^choices/(?P<k>[0-9]+)/$',\
          ChoicesView.as_view(), name='choices-get'),
      url(r'^answers/(?P<k>[0-9]+)/$',\
          AnswersView.as_view(), name='answers-post'),
      url(r'^users/(?P<uuid>[0-9]+)/answers/(?P<ver>[0-9]+)/$',\
          AnswersView.as_view(), name='latest-answers-post'),
  ]
  
new_contents: from django.conf.urls import url
  from django.contrib import admin
  from api.views import api_root, ChoicesView, QuestionsView, AnswersView, LatestAnswerView
  
  urlpatterns = [
      url(r'^$', api_root),
      url(r'^admin/', admin.site.urls),
      url(r'^questions/(?P<k>[0-9]+)/$',\
          QuestionsView.as_view(), name='questions-get'),
      url(r'^choices/(?P<k>[0-9]+)/$',\
          ChoicesView.as_view(), name='choices-get'),
      url(r'^answers/(?P<k>[0-9]+)/$',\
          AnswersView.as_view(), name='answers-post'),
      url(r'^users/(?P<uuid>([a-z]|[0-9])+)/answers/(?P<ver>[0-9]+)/$',\
          AnswersView.as_view(), name='latest-answers-post'),
  ]
  
subject: Fix regex