(variable result 0)
  (push result)
  (@)
  (push fib)
  (call)
  (push cleanup)
  (jmp)
fib
  (dup)
  (push 0)
  (=)
  (over)
  (push 1)
  (=)
  (or)
  (push recur)
  (branch)
  (return)
recur
  (dup)
  (push 1)
  (-)
  (push fib)
  (call)
  (over)
  (push 2)
  (-)
  (push fib)
  (call)
  (+)
  (nip)
  (return)
cleanup
  (push result)
  (!)
  (bye)