slicing list of lists in Python

Question

I need to slice a list of lists in python.

A = [[1,2,3,4,5],[1,2,3,4,5],[1,2,3,4,5]]
idx = slice(0,4)
B = A[:][idx]

The code above isn\'t

Answer 1

A = [[1,2,3,4,5],[1,2,3,4,5],[1,2,3,4,5]]

print [a[:3] for a in A]

Using list comprehension