public function askProjectDir(
        InputInterface $input,
        OutputInterface $output,
        $dir = null,
        SymfonyStyle $style = null
    ) {
        $question = $this->getSimpleQuestion()
            ->getQuestion('Please set your root project directory.', $dir);
        $question->setValidator(
            $this->getValidator()
        );

        $style = $style ?: new SymfonyStyle($input, $output);
        $dir   = $style->askQuestion($question);

        return rtrim($dir, '\\/');
    }