code: def retrieve(self, request, pk=None):  # pylint: disable=invalid-name
          
          catalog_api = CourseCatalogApiClient(request.user)
          catalog = catalog_api.get_catalog(pk)
          self.ensure_data_exists(
              request,
              catalog,
              error_message=(
                  "Unable to fetch API response for given catalog from endpoint '/catalog/{pk}/'. "
                  "The resource you are looking for does not exist.".format(pk=pk)
              )
          )
          serializer = self.serializer_class(catalog)
          return Response(serializer.data)
docs: DRF view to get catalog details.
  
          Arguments:
              request (HttpRequest): Current request
              pk (int): Course catalog identifier
  
          Returns:
              (Response): DRF response object containing course catalogs.