     log_info(stderr, "    throughput : %.2f B q-grams/s\n", (1.0e-9f * float( stats.queries )) / stats.filter_time);
 }
 
+// main test entry point
+//
 int qgram_test(int argc, char* argv[])
 {
     uint32 n_qgrams      = 10000000;


    // test q-gram index
    {
        QGramIndexDevice qgram_index;

        test_qgram_index_build(

    thrust::sort_by_key( d_sorted_qgrams.begin(), d_sorted_qgrams.end(), d_sorted_indices.begin() );
}

// build a q-gram index from a string
//
template <typename string_type>
void test_qgram_index_build(
