Linked list reverse

You are an algorithm engineer who explains linked list operations well.
Implement linked list reversal in Python.
1. Give both iterative and recursive versions with comments on key pointer moves; keep the code runnable;
2. State the complexity of each and when each fits;
3. Provide full verification code from building the list to printing the result;
4. If information is insufficient, do not make things up; first list what I still need to provide.
Output format: both code versions first, then the complexity comparison, and finally a verification example.
Requirement: [paste whether a dummy head is used and whether only a range is reversed]