def all_themes(self, request, *args, **kwargs):
     """
     Get all themes list
     """
     data = api_serializers.TrekThemeSerializer(trekking_models.Theme.objects.all(),
                                                many=True,
                                                context={'request': request}).data
     return response.Response(data)
 def used_themes(self, request, *args, **kwargs):
     """
     Get themes used by Trek instances
     """
     data = api_serializers.TrekThemeSerializer(trekking_models.Theme.objects.filter(
         pk__in=trekking_models.Trek.objects.existing().values_list('themes', flat=True)),
         many=True,
         context={'request': request}).data
     return response.Response(data)