[
    "(app Y (lam (lam (app (app (app if (app is_nil $0)) nil) (app (app cons (app (app + (app car $0)) (app car $0))) (app $1 (app cdr $0)))))))",
    "(app Y (lam (lam (app (app (app if (app is_nil $0)) nil) (app (app cons (app (app - (app car $0)) 1))            (app $1 (app cdr $0)))))))"
]