code: def start_threads (self):
          
          if self.config["status"]:
              t = status.Status(self, self.config["status_wait_seconds"])
              t.start()
              self.threads.append(t)
          if self.config["maxrunseconds"]:
              t = interrupt.Interrupt(self.config["maxrunseconds"])
              t.start()
              self.threads.append(t)
          num = self.config["threads"]
          if num > 0:
              for dummy in range(num):
                  t = checker.Checker(self.urlqueue, self.logger, self.add_request_session)
                  self.threads.append(t)
                  t.start()
          else:
              self.request_sessions[thread.get_ident()] = new_request_session(self.config, self.cookies)
              checker.check_urls(self.urlqueue, self.logger)
docs: Spawn threads for URL checking and status printing.