old={'l':2}
new=old
print('id(old)',id(old))
new['l']=3
print('id(new)',id(new))
print(old)
old=2
new=old
(new)=3
print('id(old)',id(old))
print('id(new)',id(new))
print(old)
输出:
id(old) 2509610372912
id(new) 2509610372912
{'l': 3}
id(old) 1609184960
id(new) 1609184992
2