def save(self, filename):
        """Save proxies to file"""
        proxies = {'http': [], 'https': []}
        for protocol in ['http', 'https']:
            for proxy in self.proxies[protocol]:
                serializable_proxy = self.proxies[protocol][proxy].to_dict()
                proxies[protocol].append(serializable_proxy)
        with open(filename, 'w') as fout:
            json.dump(proxies, fout)
Save proxies to file