This is a very simple implementation of a "fruit" machine. Nothing fancy, but
it works. Credits are earned as follows:
You start with 250 credits
with all three equal, you earn 25 credits
with first & second equal, you earn 15 credits
with second & third equal, you earn 10 credits
and first & third equal, you get 5 credits
If you reach 0 credits, just hit the again button to play again.