(def! n-fib (fn* [n]
    (if (< n 2) n                              ; base
        (+ (n-fib (- n 1)) (n-fib (- n 2)))))) ; recursive

(def! assert-fib (fn* [n expected]  ; check fibonacci result
    (if (not (= (n-fib n) expected))
        (do (prn (list
                "Expected"
                expected
                "got"
                (n-fib n)))
            (assert nil)))))      ; cause test panic

(assert-fib 0 0)
(assert-fib 1 1)
(assert-fib 2 1)
(assert-fib 3 2)
(assert-fib 4 3)
(assert-fib 5 5)
(assert-fib 6 8)