code: def get_crawler_class(self, crawler):
          
          settings = Settings()
          settings.set('SPIDER_MODULES', [self.__crawer_module])
          spider_loader = SpiderLoader(settings)
          return spider_loader.load(crawler)
docs: Searches through the modules in self.__crawer_module for a crawler with
          the name passed along.
  
          :param str crawler: Name of the crawler to load
          :rtype: crawler-class