Response headers. The engine reads them in any case, and also accepts a fetch
Headers object or a Map.
OptionalurlThe URL the response came from, if the transport knows it (fetch's response.url).
When it is on another origin than the request, the transport followed a redirect
itself and the engine rejects the response with a TagesschauNetworkError.
The body; the engine also accepts any ArrayBuffer view (a
Uint8Arrayfrom fetch) or an ArrayBuffer.