Why must an empty list be created?

hi why must an empty list be created?

We need an empty list to keep track of what values have been seen, since the first item will always be new it will go in. But any item thereafter will be compared with what is already in that list.

It’s not a must, it is an option if you’d like to store values which you encounter. However you can avoid using lists (doing via dictionary instead). Here’s a link to discussion page