TutorSyntax | Lists and subroutines
Level: GCSE

CHALLENGE
Use functions to find the total, minimum, maximum and mean of a list without using built-in min, max or sum.

1. Read the starter.py TODO comments and complete the program.
2. Test with typical values, boundary values and invalid input where appropriate.
3. Compare your work with solution.py only after making an attempt.
4. Extension: write at least three automated assert tests.

Runs with Python 3.10+ standard library; no external packages needed.
