Python-增强赋值以及共享引用

>>> L=[1,2]
>>> M=L
>>> L=L+[3,4]
>>> L,M
([1, 2, 3, 4], [1, 2])

>>> L=[1,2]
>>> M=L
>>> L+=[3,4]
>>> L,M
([1, 2, 3, 4], [1, 2, 3, 4])
>>>