Python - Paying attention when you want to copy/clone a list

if you do b = a,

you didn’t copy the list referenced by a. You just created a new tag b and attached it to the list pointed by a. Like in the picture below:

If you modify a, you also modify b, since they point to the same list.

Now we want to copy the list referenced by a. We need to create a new list to attach b to it.

b = a[:]

b = a.copy()