guests = ['lj','fw','potato']
message = guests[0] + "," + guests[1] + "," + guests[2] + ", you three guys fucking to my party!"
print(message)  #输出姓名
bitch = guests.pop()   #来不了的人,此时列表仅剩两个值
print(guests)
print(bitch)
guests.append('zkq')
message = guests[0] + "," + guests[1] + "," + guests[2] + ", you three guys fucking to my party!"  #缺了对message的重新定义，则message内容不变
print(message + '\nGuys, we have a bigger desk!')
guests.insert(0,'wxy')
print(guests)	
print(message)

最开始给message的定义是列表guests的值，后来guests里的值变了，为什么输出的时候message的内容和原来一样呢（如果不重新定义message的话）