# Recursive flattening finger exercise

> ML Prep practice item.

- Stable ID: `mit-6-100l-finger-16`
- Collection: practice
- Area: Programming
- Topic: Recursion
- Origin: external
- Difficulty: medium
- Expected time: 10 minutes
- Skills: base-case, recursive-implementation, sequence-data-structures
- Item JSON: https://mlprep.iwase.dev/item/mit-6-100l-finger-16.json

- Source: MIT 6.100L Introduction to CS and Programming using Python
- Document: Finger Exercises
- Locator: Lecture 16
- Original problem: https://ocw.mit.edu/courses/6-100l-introduction-to-cs-and-programming-using-python-fall-2022/pages/finger-exercises/#finger-exercise-lecture-16
- Official answer: https://ocw.mit.edu/courses/6-100l-introduction-to-cs-and-programming-using-python-fall-2022/resources/mit6_100l_f22_ex16_sol_pdf/
- Answer status: official-solution


## Tutoring contract

Ask for the learner's attempt, begin with the smallest useful hint, preserve item ID `mit-6-100l-finger-16`, and record a real attempt with `recorded_by: "agent"` and `agent_session_id` when available using https://mlprep.iwase.dev/schema/attempt-record.json.