Create this Beer project:
Beer
+ Beer Folder
  + [->] BeerRuleset
         + v bottles : integer initially 99
         + v letsDrink : boolean initially false
         + v weNeedToShop : boolean initially false
         + v sing : boolean initially true
         + [->] singRule
                if sing then
                {
                  print(BottleText(bottles, true) " on the wall, " BottleText(bottles, false) ".");
                  sing is false;
                  letsDrink is (bottles is not equal to 0);
                  weNeedToShop is (bottles is 0);