protected function checkEnvironment()
    {
        if (OS::is(OS::WIN)) {
            $this->error('Swoole extension doesn\'t support Windows OS.');

            exit(1);
        }

        if (! extension_loaded('swoole')) {
            $this->error('Can\'t detect Swoole extension installed.');

            exit(1);
        }

        if (! version_compare(swoole_version(), '4.3.1', 'ge')) {
            $this->error('Your Swoole version must be higher than `4.3.1`.');

            exit(1);
        }
    }