>>> a=[0,1,2,3,4,5,6,7,8,9]
>>> a[3:7]
[3, 4, 5, 6]
>>> a[3:3]
[]
>>> a[5:]
[5, 6, 7, 8, 9]
>>> a[:5]
[0, 1, 2, 3, 4]
>>> a[-3:-1]
[7, 8]
>>> a[-5:]
[5, 6, 7, 8, 9]
>>> a[:]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]