old_contents: from django.conf.urls import patterns, url
  from api.region import views
  
  
  urlpatterns = patterns(
      '',
      url(r'^$', views.RegionList.as_view(), name='region-list'),
      url(
          r'^/(?P<pk>[0-9]+)$',
          views.RegionDetail.as_view(),
          name='region-detail'
      ),
      url(
          r'^/(?P<pk>[0-9]+)/countries$',
          views.RegionCountries.as_view(),
          name='region-countries'
      ),
      url(
          r'^/(?P<pk>[0-9]+)/activities$',
          views.RegionActivities.as_view(),
          name='region-activities'
      ),
  )
  
new_contents: from django.conf.urls import patterns, url
  from api.region import views
  
  
  urlpatterns = patterns(
      '',
      url(r'^$', views.RegionList.as_view(), name='region-list'),
      url(
          r'^/(?P<pk>[A-Za-z0-9]+)$',
          views.RegionDetail.as_view(),
          name='region-detail'
      ),
      url(
          r'^/(?P<pk>[A-Za-z0-9]+)/countries$',
          views.RegionCountries.as_view(),
          name='region-countries'
      ),
      url(
          r'^/(?P<pk>[A-Za-z0-9]+)/activities$',
          views.RegionActivities.as_view(),
          name='region-activities'
      ),
  )
  
subject: Fix region resolve on non Integer