public Result one() {
        final List<Result> results = some(1).join();

        assert results.size() <= 1;

        return results.size() == 1 ? results.get(0) : null;
    }
Get the next {@link Result} from the stream, blocking until one is available.
gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/ResultSet.java