Md Sohail — R23-T021: Make data_structures/linked_list/skip_list.py fully typed #3

Student: Md Sohail

Task: R23-T021 · 1 of 10
Repository: https://github.com/S-AI-Projects/TheAlgorithms-Python
Assigned working branch: student/e26b07f0850

Goal

Add accurate type hints so the type checker CI runs (ty) has nothing to report for this file. Functions missing hints: __iter__, _locate_node, traverse_keys, is_sorted. Four functions lack hints in a generic SkipList[KT, VT] – keep the generics consistent.

Steps

1. Run uv run --python 3.15 --with ty ty check data_structures/linked_list/skip_list.py (as in .github/workflows/ty.yml) and save the output.
2. Add parameter and return types for every function; prefer precise types (e.g. list[list[int]]) over Any.
3. Fix any real bug the checker exposes, and add a doctest for it.
4. Run the doctests to confirm behaviour is unchanged.
5. Make the code change in the repository: data_structures/linked_list/skip_list.py: type hints for the 4 unhinted functions, consistent with SkipList[KT, VT]. Re-run the automated check and the repo's own tests afterwards.
6. Prepare the PR: on branch R23-T021, commit the code change plus your work/R23-T021/ evidence, put your findings in the PR description and open the PR against the org fork. For a later upstream PR, create a second branch containing only the code change (no work/ folder).

Done when

☐ data_structures/linked_list/skip_list.py: iter, locate_node, traverse_keys and is_sorted gain hints consistent with SkipList[KT, VT].
☐ ty output before/after in the PR, ending clean for this file.
☐ The file's test* functions and 32 doctests still pass.

Submission checklist

• Complete this task and its checks.
• Add the required evidence and link your pull request here.
• Select this S-AI-Projects fork as the PR base repository.
• Request instructor review.

Keep this PR focused on this task. Do not submit assignment PRs to the upstream repository.