0x40Lesson 5 of 6

Write reusable functions

Define functions, pass arguments and return results.

12 min 5-question quiz 1 code exercise

By the end of this lesson you can

Create a function that accepts input and returns a value.

A function packages reusable work. Define one with def, give it a name and parameters, then indent its body. return sends a result back to the caller; print only displays a value.

main.py

1def greet(name):
2    return "Hello, " + name
3
4print(greet("Sam"))

Output

Hello, Sam

Parameters are names listed in the definition; arguments are values supplied when calling the function. A function without an explicit return gives back None.

Key takeaways

Create a function that accepts input and returns a value.
Read the output to check what your program did.
Keep indentation consistent in Python blocks.

Lesson quiz

5 questions · pass with 4 correct · up to 50 XP

Passing this quiz completes the lesson and keeps your streak going. Questions you miss come back in review sessions later.

Practice: write Python

Write Python in the editor and run it against sample inputs. Python runs locally in your browser using a WebAssembly runtime.

Exercise 1

Create a greeting function

+25 XP

Define greet(name) so it returns Hello, followed by the supplied name. Read one name and print the function result.

Greet Ada
Greet Lin

main.py

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Python runs in a sandboxed browser worker with a 60 second time limit. Its runtime loads from the Pyodide CDN; your code stays in this browser.

Questions about this lesson

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