Def Params.

Chapter 4 — Functions. In Foundations you already wrote def and return. Today is a brief review, then we go deeper.

A function is a named recipe. Parameters are the names in the parentheses at def. Arguments are the values you pass when calling.

def double(n):
    return n * 2

value = double(7)

return sends a value back to the caller. print shows something on screen — that is not the same (we refine this later).

Common mistake: calling without parentheses; or forgetting return and expecting a magic result.