Python list 切片操作技巧 3 则

片段1：

>>> lst = [1, 2, 3, 4, 5]
>>> del lst[:]
>>> lst
[]

片段2：

>>> a = lst
>>> lst[:] = [7, 8, 9]
>>> lst
[7, 8, 9]
>>> a
[7, 8, 9]
>>> a is lst
True

片段3：

>>> b = lst[:]
>>> b
[7, 8, 9]
>>> b is lst
False