If DEBUG: raise NotImplemented Exception.
        If not, raise 404.
        :raises:`django.http.Http404` if production environment.
        :raises:`NotImplementedError` if ``settings.DEBUG`` is True

def not_implemented(self, context, **response_kwargs):
        '''
        If DEBUG: raise NotImplemented Exception.
        If not, raise 404.
        :raises:`django.http.Http404` if production environment.
        :raises:`NotImplementedError` if ``settings.DEBUG`` is True
        '''
        if settings.DEBUG:
            raise NotImplementedError(_('This export type ({})is not yet supported.'.format(self.format)))
        raise Http404