how to slice a tuple list giving out specifc order elemtn code example

Example 1: slicing in python list

a = [1,2,3,4,5]
a[m:n] # elements grrater than equal to m and less than n
a[1:3] = [2,3]

Example 2: python slice second element of list of lists

import numpy as np

A = np.array([[1,2,3,4,5],[1,2,3,4,5],[1,2,3,4,5]])
A[:,:3]

Out[3]: 
array([[1, 2, 3],
       [1, 2, 3],
       [1, 2, 3]])