colon in array python

1a[start:stop]  # items start through stop-1
2a[start:]      # items start through the rest of the array
3a[:stop]       # items from the beginning through stop-1
4a[:]           # a copy of the whole array

1>>> a=[1,2,3,4,5]
2>>> a[1:3]
3[2, 3]
4>>> a[:3]
5[1, 2, 3]
6>>> a[2:]
7[3, 4, 5]
8>>> s='computer'
9>>> s[:3]
10'com'
11>>> s[3:6]
12'put'