>>> list = [1,2,3,4,5,6,7,8,9,10]
>>> list[0:5]
[1, 2, 3, 4, 5] #返回一个列表
>>> list[0:-1]
[1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list[0:-3]
[1, 2, 3, 4, 5, 6, 7]
>>> list[3:]
[4, 5, 6, 7, 8, 9, 10]
>>> list[3:-1]
[4, 5, 6, 7, 8, 9]
>>> list[:4]
[1, 2, 3, 4]
>>> list[:-1]
[1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list[-1:4]
[]