code: def start(self):
          
          self._lock.acquire()
          try:
              if not self.is_alive():
                  self._thread = threading.Thread(target=self._target, name="raven.AsyncWorker")
                  self._thread.setDaemon(True)
                  self._thread.start()
                  self._thread_for_pid = os.getpid()
          finally:
              self._lock.release()
              atexit.register(self.main_thread_terminated)
docs: Starts the task thread.