hill cipher

Have a function with the name “hill_enc” that accepts a Matrix (3×3) as its first argument and a string as its second argument and returns a string. This function should make sure that the processed input string is padded with “X” or “XX” to make the input length a multiple of 3.
e.g., function call: hill_enc(M, ‘Test String’) should return a string ‘BPBLJCPRGHQO’; where M has the value as shown in the code snippet below:
using numpy as np
M = np.array([[17,17,5],[21,18,21],[2,2,19]])