code: def enqueue(self, message, *, delay=None):
          
          queue_name = message.queue_name
          if delay is not None:
              queue_name = dq_name(queue_name)
              message_eta = current_millis() + delay
              message = message.copy(
                  queue_name=queue_name,
                  options={
                      "eta": message_eta,
                  },
              )
  
          if queue_name not in self.queues:
              raise QueueNotFound(queue_name)
  
          self.emit_before("enqueue", message, delay)
          self.queues[queue_name].put(message.encode())
          self.emit_after("enqueue", message, delay)
          return message
docs: Enqueue a message.
  
          Parameters:
            message(Message): The message to enqueue.
            delay(int): The minimum amount of time, in milliseconds, to
              delay the message by.
  
          Raises:
            QueueNotFound: If the queue the message is being enqueued on
              doesn't exist.