sub benchmark_routine
{
    my ($testFn, $testName)=@_;

    foreach(@testCases) {
        my ($sentence, $wantedLetters, $expectedResult) = @$_;
		$testFn->($sentence, $wantedLetters) for (1..20);
        die "$testName test failed ($sentence, $wantedLetters)"
          unless (($testFn->($sentence, $wantedLetters))==$expectedResult);
    }
}