private function setInputAndOutput(InputInterface $input, OutputInterface $output)
    {
        if (is_null($this->assistant)) {
            $this->assistant = new CommandAssistant();
            $this->assistant->setQuestionHelper($this->getQuestionHelper());
            $this->assistant->setKernel($this->getApplication()->getKernel());
        }
        $this->assistant->setOutput($output);
        $this->assistant->setInput($input);
    }