code: def get_countries(self):
          
          qs = Venue.objects.values('country') \
                                      .exclude(country='') \
                                      .distinct() \
                                      .order_by('country')
  
          countries = []
  
          for c in qs:
              countries.append({
                  'code': c['country'],
                  'name': Venue.get_country_name(c['country'])
              })
  
          return sorted(countries, key=lambda k: k['name'])
docs: Returns a list of dicts, one per country that has at least one Venue
          in it.
  
          Each dict has 'code' and 'name' elements.
          The list is sorted by the country 'name's.