# Evaluates to AST_NUM 6765.

let plus = rec p =>
      fn x => fn y => if iszero x then y else p (pred x) (succ y)
in
  let fibonacci = rec f =>
	fn n => if iszero n then
		  0
		else if iszero (pred n) then
		  1
		else
		  plus (f (pred n)) (f (pred (pred n)))
  in
    fibonacci 20
  end
end