public static void prev(String query,
int limit, String sortkey,
AsyncCallback<ChangeList> callback) {
RestApi call = newQuery(query);
if (limit > 0) {
call.addParameter("n", limit);
}
if (!PagedSingleListScreen.MIN_SORTKEY.equals(sortkey)) {
call.addParameter("P", sortkey);
}
call.send(callback);