@Override
        public Pong ping(Ping ping,Searcher searcher) {
            return new Execution(searcher, Execution.Context.createContextStub()).ping(ping);
        }
A cluster searcher which clusters over a set of alternative searchers (search chains would be more realistic)
container-search/src/test/java/com/yahoo/search/cluster/test/ClusterSearcherTestCase.java