code: public function start($env)
      {
          switch ($env) {
              case 'dev':
                  ini_set('display_errors', 1);
                  error_reporting(1);
                  $this->initWhoops();
                  break;
              case 'test':
              case 'prod':
                  ini_set('display_errors', 0);
                  error_reporting(E_ALL & ~E_NOTICE & ~E_DEPRECATED & ~E_STRICT & ~E_USER_NOTICE & ~E_USER_DEPRECATED);
                  break;
              default:
                  header('HTTP/1.1 503 Service Unavailable.', true, 503);
                  die('The application environment is not set correctly.');
          }
  
          if (file_exists(storage_path('app.down'))) {
              throw new ExceptionHandler('The system is under maintenance.', 'We will be back very soon.');
          }
  
          if (! $this->hasBeenBootstrapped()) {
              $this->bootstrap();
          }
  
          require $this->path('routes.php');
          $this->app['route']->run();
      }
docs: Kernel start
  
  @param string $env
  
  @return void