code: def shutdown(self):
          
          self.signal_children(signal.SIGABRT)
  
          # Wait a few iterations when trying to stop children before terminating
          waiting = 0
          while self.living_children:
              time.sleep(0.5)
              waiting += 1
              if waiting == self.MAX_SHUTDOWN_WAIT:
                  self.signal_children(signal.SIGKILL)
                  break
docs: Send SIGABRT to child processes to instruct them to stop