[R-sig-Geo] leaflet problem

[Erich Subscriptions]

I am creating clickable maps with leaflet and experiencing a problem.

The documentation seems not to indicate how to specify an urlTemplate for multiple urls
I want to use
http://maps{s}.wien.gv.at/basemap/bmapgrau/normal/google3857/{z}/{y}/{x}.png <http://maps{s}.wien.gv.at/basemap/bmapgrau/normal/google3857/{z}/{y}/{x}.png>
with the possible values for {s}
'','1','2','3','4'

How do I specify this?
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