class BaseHandler(object):

    def crawl(self, url, **kwargs):
        if kwargs.get(‘callback‘):
            callback = kwargs[‘callback‘]
            if isinstance(callback, basestring) and hasattr(self, callback):
                func = getattr(self, callback)
            elif hasattr(callback, ‘im_self‘) and callback.im_self is self:
                func = callback

        resp = requests.get(url)
        return func(resp)


class Anjuke(BaseHandler):
    def on_start(self):
        self.crawl(start_url, callback=self.index_url)

    def index_url(self, response):
        print response.text

a = Anjuke()
print a.on_start()