(defun fn (x) (cond (test-condition1 the-value1) (test-condition2 the-value2) ... ... ... (t (fn reduced-argument-x)))) CL-USER 2788 > (defun my-fib (n) (cond ((= n 1) 1) ((= n 2) 1) (t (+ (my-fib (- n 1)) (my-fib (- n 2)))))) MY-FIB CL-USER 2789 > (my-fib 1) 1 CL-USER 2790 > (my-fib 2) 1 CL-USER 2791 > (my-fib 3) 2 CL-USER 2792 > (my-fib 4) 3 CL-USER 2793 > (my-fib 5) 5 CL-USER 2794 > (my-fib 6) 8 CL-USER 2795 > (my-fib 7) 13