code: def scan(self):
          
          self.logger.info('{0} registered scan functions, starting {0} threads '
                           'to scan candidate proxy lists...'
                           .format(len(self.scan_funcs)))
          for i in range(len(self.scan_funcs)):
              t = threading.Thread(
                  name=self.scan_funcs[i].__name__,
                  target=self.scan_funcs[i],
                  kwargs=self.scan_kwargs[i])
              t.daemon = True
              self.scan_threads.append(t)
              t.start()
docs: Start a thread for each registered scan function to scan proxy lists