TutorSyntax A-level Python | Lesson 1: Recursion and call stacks

Learning goal: Write a recursive factorial function with a base case.

1. Read the worked example on the site.
2. Complete the starter without looking at the solution.
3. Add normal, boundary and invalid tests.
4. Compare with the reference solution; explain your improvements.

A-level note: OCR H446 algorithms / AQA 7517 recursion. These are original practice materials, not endorsed exam-board tasks.
