Request to merge exercise 4 performed to the main branch

[JesFusion]

This pull request adds a new utility function checkerboard(n) to address Exercise 4.
This function generates an (N x N) NumPy array that mimics a checkerboard pattern using alternating ones and zeros.

Key Changes:

1. New Functionality: Implements the logic to create a dynamic (N x N) checkerboard array using numpy operations.
2. Input Validation: Adds basic error handling using a try-except block to ensure the input parameter n is a valid integer.
3. Array Manipulation: Utilizes numpy slicing (::2) within a loop to efficiently set alternating rows and columns to the desired values (0 or 1).
4. Code Structure: Fulfills the requirements outlined in the associated exercise.