How to get response.context information on the client side in an Angular application?

So I am trying to create an Angular application and the server end point sends the following information (it's created in Python).

 gltf = create_gltf(vertices, trig_faces, uv)
        data = b"".join(gltf.save_to_bytes())
        data_size = {"size": len(data)}
        log.info(f"Length of the content is  {len(data)}")
        response.content_type = MEDIA_GLTF
        response.context = data_size
        response.data = b"".join(gltf.save_to_bytes())
        response.status = falcon.HTTP_200

On the client side, I have used fetch api to receive the server response. It is stated below as the following:

const data$ = new Observable(observer => {
            fetch(targetUrl.toString(), { headers: { 'responseType': 'application/octet-stream' }, method: 'GET' })
                .then(response => response.arrayBuffer())
                .then(gltf => {
                    observer.next(gltf);
                    observer.complete();
                })
                .catch(err => observer.error(err));
        });
        let result = data$.pipe(
            map(gltfAsArrayBuffer => {
                let gltfObject: any = {
                    'componentId': componentId,
                    'gltfBytes': gltfAsArrayBuffer,
                };
                    this.surfaceMeshesGltf.set(surfaceMeshKey, gltfObject);
            })
        );
        return result;

I was wondering how do I access the context information that I am sending over from the backend on the client side (the context information in this case is the size of the data being sent).