ipfehoe.py

list_of_list = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]




def make_diagonal(list_of_lists):
    diag = []
    [list_of_lists[len(list_of_lists)-x-1][x] for x in range(len(list_of_lists))]
    x.append(x)
    [list_of_lists[x][x] for x in range(len(list_of_lists))]
    diag.append(x)
    
    list_of_lists.extend(diag)

    print(list_of_lists)



make_diagonal(list_of_list)