import copy

a = [[1, 2, 3], [4, 5, 6]]
b = a
print("a and b before modify")
print(a)
print(b)
a[0][1] = 10
print("a and b after modfiy. b was obtain as a copy of a")
print(a)
print(b)

b = copy.deepcopy(a)
print("a nad b before modify")
print(a)
print(b)
a[0][1] = 9
print("a and b after modify")
print(a)
print(b)