Fix for Python

Python fork which adds the check for user solution on if it's a valid Regex expression and catches the exception on such.
UPD: also plainified all random test inputs to show so that it wouldn't cause a HTML hell in a frame

Great

This is insightful.

smart!

Approved

python new test framework is required. updated in this fork

Input range needs to be specified. (Because apparently the input only goes up to 500, which makes this kata extremely easy)

Instructions mention it should return "Invalid date" but the tests are testing for "Invalid date!" (in those cases)

The approximation formula could use extra parentheses, to reduce ambiguity.
Currently, it says "π * (3/2(a+b) - sqrt(ab))"
Perhaps it should say "π * ((3/2)(a+b) - sqrt(ab))"

Just to be clear that it isn't 3/(2(a+b))

C Translation

Python, possibly other languages: tests miss sanity checks on values returned by user solution and crash badly when an unexpected value (not a pattern, or not a valid pattern) is returned.