lis = [5, 8, 'x', ['yy', 202, ['k3', ['aa', 2, '5']], 78], 'ca', 'sdv']
lis[3][2][1][:1] = ['AA']
lis[3][2][1][0] = lis[3][2][1][0].upper()
lis[-3][-2][-1][0] = "AA"
lis[-3][-2][-1][0].upper()