Lesson 3: Where names live, and functions as values

Module 6 · Lesson 3 · About 45 minutes · Needs: Module 6 Lessons 1 and 2 (def, return, parameters), Module 5 (lists, dictionaries, comprehensions)

The situation

Amira likes the functions from Lessons 1 and 2: days_late(21, 44) says Ben is 9 days late every time. Now she wants the overdue loans in order, most owed first, so she knows whom to call. And she wants proof that the fee rule is right before it touches the charity jar.

That needs three ideas: which names a function can see, how to hand one function to another, and how to check a function in one line.