A function is a command you make yourself. You give it a name, tell it what it needs, and say what it should give back. Then you can use it as many times as you like.

def greet(name: str) -> str:
    return f"Ahoy, {name}!"

message = greet("Ada")
print(message)

• def starts a function. greet is its name.
• name: str is a parameter: something the function needs. The : str says it should be text.
• -> str says the function returns text.
• return sends the answer back to whoever called the function.
• Calling greet("Ada") runs the function with name set to "Ada".

Press Run, then try to:

• Call greet with your own name.
• Write a function double(number: int) -> int that returns the number times two.
• What does print(cheer()) print, and why? (Hint: -> None)

Finish the two functions. is_even should return True for even numbers. biggest should return the bigger of two numbers.

Put is_even and biggest into main.py in your project. Then add tests:

from main import biggest, greet, is_even


def test_greet():
    assert greet("Ada") == "Hello, Ada!"


def test_is_even():
    assert is_even(4) is True
    assert is_even(7) is False


def test_biggest():
    assert biggest(3, 9) == 9

uv run pytest

That is exactly what the exercise checker on this page does: it calls your functions and checks the answers.