Parrot Refactoring Kata
Can you spot any code smells in this code? I'll give you a clue - a spot of Pol(l)ymorphism should improve matters!
Refactor this code, take small steps, run the tests often. See how small and beautiful you can make it.
This code is heavily inspired by one of the examples in Martin Fowler's book "Refactoring". It's a classic, and if it's not on your bookshelf already I suggest you treat yourself to a copy!