我有一个用python编程的discord机器人。我希望机器人说笑话的第一部分，即time.sleep，然后讲笑话的第二部分（都在同一个变量中）。这是我的代码：
if message.content.startswith('!joke'):
a = 'Can a kangaroo jump higher than a house?' + time.sleep(3) + 'Of course, a house doesn’t jump at all.'
b = 'Anton, do you think I’m a bad mother?' + time.sleep(3) + 'My name is Paul.'
c = 'Why can\'t cats work with a computer?' + time.sleep(3) + 'Because they get too distracted chasing the mouse around, haha!'
d = 'My dog used to chase people on a bike a lot.' + time.sleep(3) + 'It …