docs: def process_resource(self, req, resp, resource):
          """ Process the request after routing.
  
          Serializer selection needs a resource to determine which
          serializers are allowed.
          """
  
          if resource:
              allowed = resource.serializer_mimetypes
              preferred = req.client_prefers(allowed)
  
              if not preferred:
                  abort(RequestNotAcceptable(allowed))
              else:
                  serializer = self._get_serializer(preferred)
                  resp.serializer = serializer(req, resp)