Make_Simple.ExtSourceval unlisten :
?sitedata:Eliom_common.sitedata ->
([< `Client_process ], [< `Data ]) Eliom_state.Ext.state ->
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.