define("fib(a)")  :(fib_end)
fib   fib = lt(a,2) a   :s(return)
   fib = fib(a - 1) + fib(a - 2) :(return)
fib_end

while a = trim(input)   :f(end)
   output = a " " fib(a)   :(while)
end