Comment by zahlman

It has indeed not changed. But practically speaking it doesn't matter much. The string implementation cheats by using resizable buffers internally for at least some purposes, while presenting an immutable-type interface. But regardless, a given line of code is going to have O(1) such additions; it's not remotely as bad as `for i in items: str += foo(i)`. (This should be done using `''.join` instead.)