code: func NegotiateOutputMediaTypeStream(req *http.Request, ns runtime.NegotiatedSerializer, restrictions EndpointRestrictions) (runtime.SerializerInfo, error) {
  	mediaType, ok := NegotiateMediaTypeOptions(req.Header.Get("Accept"), ns.SupportedMediaTypes(), restrictions)
  	if !ok || mediaType.Accepted.StreamSerializer == nil {
  		_, supported := MediaTypesForSerializer(ns)
  		return runtime.SerializerInfo{}, NewNotAcceptableError(supported)
  	}
  	return mediaType.Accepted, nil
  }
docs: // NegotiateOutputMediaTypeStream returns a stream serializer for the given request.