def crawl(url, callback, **kwargs):
    """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

    """
    timeout = kwargs.pop('timeout', DEFAULT_TIMEOUT)
    return wait_for(timeout, _crawl_in_reactor, url, callback, **kwargs)
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