docs: def shutdown(self, wait=True):
      """
      Shut down the pool. If *wait* is True, it will wait until all futures
      are completed. Alternatively, you can use the #wait() method to wait
      with timeout supported.
      """
  
      with self._lock:
        self._shutdown = True
        self._lock.notify_all()
      if wait:
        self.wait()