protected function executeDecorators($command)
    {
        foreach ($this->decorators as $className)
        {
            $instance = $this->app->make($className);

            if ( ! $instance instanceof CommandBus)
            {
                $message = 'The class to decorate must be an implementation of Laracasts\Commander\CommandBus';

                throw new InvalidArgumentException($message);
            }

            $instance->execute($command);
        }
    }