Scan candidate proxies from http://ip84.com

        Args:
            region: Either 'mainland' or 'overseas'.
            page: An integer indicating how many pages to be scanned.

def scan_ip84(self, region='mainland', page=1):
        """Scan candidate proxies from http://ip84.com

        Args:
            region: Either 'mainland' or 'overseas'.
            page: An integer indicating how many pages to be scanned.
        """
        self.logger.info('start scanning http://ip84.com for proxy list...')
        for i in range(1, page + 1):
            if region == 'mainland':
                url = 'http://ip84.com/dlgn/{}'.format(i)
            elif region == 'overseas':
                url = 'http://ip84.com/gwgn/{}'.format(i)
            else:
                url = 'http://ip84.com/gn/{}'.format(i)
            response = requests.get(url)
            soup = BeautifulSoup(response.content, 'lxml')
            table = soup.find('table', class_='list')
            for tr in table.find_all('tr'):
                if tr.th is not None:
                    continue
                info = tr.find_all('td')
                protocol = info[4].string.lower()
                addr = '{}:{}'.format(info[0].string, info[1].string)
                self.proxy_queue.put({'addr': addr, 'protocol': protocol})