How may I copy a list of list without reference?

Python Help
1

I can copy a list without reference

a = [3,4,5]
b = a.copy()
b[0] = -1
print(a)
print(b)
>>[3, 4, 5]
>>[-1, 4, 5]

but why can’t I do the same for a list of list? What should I do?

a = [[1,1],[1,1]]
b = a.copy()
b[0][0] = -1
print(a)
print(b)
>>[[-1, 1], [1, 1]]
>>[[-1, 1], [1, 1]]
2

The terms in question are: “shallow-copy” and “deep-copy”.

Web.Refs: