code: def _crawl_in_reactor(url, callback, spider_cls=DefaultSpider, **kwargs):
      
      spider_cls = override_start_requests(spider_cls, [url], callback)
      return _run_spider_in_reactor(spider_cls, **kwargs)
docs: Crawls given URL with given callback.
  
      Parameters
      ----------
      url : str
          The URL to crawl.
      callback : callable
          Function to be used as callback for the request.
      spider_cls : scrapy.Spider (default: DefaultSpider)
          A spider class to be used in the crawler instance.
      kwargs : dict, optional
          Extra arguments to be passed to ``_run_spider_in_reactor``.
  
      Returns
      -------
      crochet.EventualResult