Track 9 · Lesson 5 of 11

Raising exceptions

Signal problems from your own functions with raise, choose the right exception type, write messages that help, and re-raise or chain when translating errors.

You will be able to

• Raise a built-in exception with raise and an informative message
• Choose between ValueError, TypeError and KeyError for a given problem
• Explain why raising is better than returning an error string or a magic value
• Re-raise an exception with a bare raise, and translate one with raise ... from