Python · Errors and files

assert

A development-time check. Assertions can be stripped with -O, so never use them for validation.

pythonRunnable example python course

Syntax

assert condition, "message"

Example

Open in the lab

score = 84
assert score >= 0, "score must not be negative"
print("ok")

Reference pages are the quick answer. The course explains the why, shows the full example and ends with a challenge.