public Searcher searcher() {
        return new Searcher();
    }
@Test
    void requireThatPredicateIndexCanSearchWithEmptyDocuments() {
        PredicateIndexBuilder builder = new PredicateIndexBuilder(10);
        builder.indexDocument(1, Predicate.fromString("true"));
        builder.indexDocument(2, Predicate.fromString("false"));
        PredicateIndex index = builder.build();
        PredicateIndex.Searcher searcher = index.searcher();
        PredicateQuery query = new PredicateQuery();
        assertEquals("[1]", searcher.search(query).toList().toString());
    }