# Tasks that exercise the guidance — realistic requests a coding assistant gets daily.
# Evolution rewards guidance that makes responses handle edge cases, errors, and tests.

Add a function that parses ISO-8601 date strings from user input, including how invalid input should be handled.

Fix this bug and explain the fix: `def avg(xs): return sum(xs) / len(xs)` crashes when xs is empty.

Add a --verbose flag to an argparse-based CLI script, and update its usage documentation.
