module Ext:sig..end
val unlisten : ?sitedata:Eliom_common.sitedata ->
([< `Client_process ], [< `Data ]) Eliom_state.Ext.state ->
Eliom_notif.S.key -> unitMake a listener stop listening on data key.
If this function is called during a request it will be able to determine
sitedata by itself, otherwise it needs to be supplied by the caller.