Return vs. Print: The Mysterious None, and Functions in Real Code

Why does a function that prints instead of returns hand back a mysterious None — and how does a function live in memory as an object bound to a name?

Finger exercises

Short drills on what this video just taught. Write the code, run the checks, and reveal the answer only if you are stuck.

0 / 5 passed

Exercise 1 of 5

Return, don't print

Here is the specification. Write a function div_by(n, d), where n and d are integers greater than 0, that gives back True when d divides n evenly and False when it does not. Then call div_by(80, 4) and store the value it hands back in divides.

Hint: % gives the remainder of a division, == compares two values, and return (not print) is what hands a value back to the caller.

def div_by(n, d):
    ...  # your code here — return the True/False answer (don't print it)

divides = ...  # your code here — call div_by(80, 4) and store what it returns

def div_by(n, d):
    ...  # your code here — return the True/False answer (don't print it)

divides = ...  # your code here — call div_by(80, 4) and store what it returns

Python runs in your browser

⌘/Ctrl + Enter runs

is True or False, not None

is what div_by(80, 4) hands back

div_by also says False when the division is not exact

←Previous How a Function Call Becomes Its Value: Parameters vs. Arguments Next Building sum_odds: Plan on Paper, Then Catch the Off-by-One Bug →