bslatkin

    ---- THIS ----

    (defun sum-helper (items total)
        (cond
            (items
                (sum-helper
                    (cdr items)
                    (+ total (car items))))
            (t total)))

    (defun sum (&rest items)
        (sum-helper items 0))

    (print (sum 1 2 3 4))

    ----- OR -----

    (defun sum-helper2 (items total)
        (if (not items)
            (return-from sum-helper2 total))

        (sum-helper2
            (cdr items)
            (+ total (car items))))

    (defun sum2 (&rest items)
        (sum-helper2 items 0))

    (print (sum2 5 6 7 8))