def crawl(self, crawler_or_spidercls, *args, **kwargs):
        """
        Run a crawler with the provided arguments.

        It will call the given Crawler's :meth:`~Crawler.crawl` method, while
        keeping track of it so it can be stopped later.

        If ``crawler_or_spidercls`` isn't a :class:`~scrapy.crawler.Crawler`
        instance, this method will try to create one using this parameter as
        the spider class given to it.

        Returns a deferred that is fired when the crawling is finished.

        :param crawler_or_spidercls: already created crawler, or a spider class
            or spider's name inside the project to create it
        :type crawler_or_spidercls: :class:`~scrapy.crawler.Crawler` instance,
            :class:`~scrapy.spiders.Spider` subclass or string

        :param list args: arguments to initialize the spider

        :param dict kwargs: keyword arguments to initialize the spider
        """
        if isinstance(crawler_or_spidercls, Spider):
            raise ValueError(
                'The crawler_or_spidercls argument cannot be a spider object, '
                'it must be a spider class (or a Crawler object)')
        crawler = self.create_crawler(crawler_or_spidercls)
        return self._crawl(crawler, *args, **kwargs)

        Run a crawler with the provided arguments.

        It will call the given Crawler's :meth:`~Crawler.crawl` method, while
        keeping track of it so it can be stopped later.

        If ``crawler_or_spidercls`` isn't a :class:`~scrapy.crawler.Crawler`
        instance, this method will try to create one using this parameter as
        the spider class given to it.

        Returns a deferred that is fired when the crawling is finished.

        :param crawler_or_spidercls: already created crawler, or a spider class
            or spider's name inside the project to create it
        :type crawler_or_spidercls: :class:`~scrapy.crawler.Crawler` instance,
            :class:`~scrapy.spiders.Spider` subclass or string

        :param list args: arguments to initialize the spider

        :param dict kwargs: keyword arguments to initialize the spider
        
stackoverflow/venv/lib/python3.6/site-packages/scrapy/crawler.py