code: def load(self, filename):
          
          with open(filename, 'r') as fin:
              proxies = json.load(fin)
          for protocol in proxies:
              for proxy in proxies[protocol]:
                  self.proxies[protocol][proxy['addr']] = Proxy(
                      proxy['addr'], proxy['protocol'], proxy['weight'],
                      proxy['last_checked'])
                  self.addr_list[protocol].append(proxy['addr'])
docs: Load proxies from file