(defun inlist? (e l) (cond ((endp l) nil) ((= (car l) e) T) (t (inlist? e (cdr l))))) (defun no-dups (loe) (cond ((endp loe) nil) ((not (inlist? (car loe) (cdr loe))) (cons (car loe) (no-dups (cdr loe)))) (t (no-dups (cdr loe)))))