For extra credit, first define your Leap Day Baby rule, and then implement it correctly. For instance, the rule I most commonly use is Feb 29th birthdays fall on Feb 29th in years where it exists, and on Feb 28th otherwise. Another rule that's just as valid is use Feb 29th in years where it exists, and Mar 1st otherwise.

For credit, first implement it, and then figure out what Leap Day Baby rule you happened to implement, and document that.