OptionalbaseBackend base URL.
This value is always to be supplied when a loader is calling.
Additionally you should not supply this param a value as it is a
requirement that all fetchers ignore it and obtain the backend.url
via the BackendProvider from the nearest BackendLayout.
OptionalsignalRequest signal.
URL for the request to be made against.
These parameters are used by all fetchers.
Since
0.13.0