Python's list type is implemented as a dynamic array in CPython. This is not required. An optimizing Python doing escape analysis could see a list was going to

Python's list type is implemented as a dynamic array in CPython. This is not required. An optimizing Python doing escape analysis could see a list was going to be converted to a set and swap in a set and change the method calls. Or it could see a large number of concatenations and use a linked list as an intermediate form.