code: def crawl(url, callback, **kwargs):
      
      timeout = kwargs.pop('timeout', DEFAULT_TIMEOUT)
      return wait_for(timeout, _crawl_in_reactor, url, callback, **kwargs)
docs: Crawls an URL with given callback.
  
      Parameters
      ----------
      url : str
          An URL to crawl.
      callback : callable
          A function to be used as spider callback for the given URL.
      spider_cls : scrapy.Spider (default: DefaultSpider)
          A spider class to be used in the crawler instance.
      capture_items : bool (default: True)
          If enabled, the scraped items are captured and returned.
      return_crawler : bool (default: False)
          If enabled, the crawler instance is returned. If ``capture_items`` is
          enabled, the scraped items is collected in ``crawler.items``.
      settings : dict, optional
          Custom crawler settings.
      timeout : int, (default: DEFAULT_TIMEOUT)
          Result wait timeout.
  
      Returns
      -------
      out
          By default, the scraped items. If ``return_crawler`` is ``True``,
          returns the crawler instance.
  
      Raises
      ------
      crochet.TimeoutError