```lisp
;;; testing.lisp
;;; by Philip Fong
;;;
;;; Introductory comments are preceded by ";;;"
;;; Function headers are preceded by ";;"
;;; Inline comments are introduced by ";"
;;;
;;
;; Triple the value of a number
;;
(defun triple (X)
"Compute three times X." ; Inline comments can
(* 3 X)) ; be placed here.
;;
;; Negate the sign of a number
;;
(defun negate (X)
"Negate the value of X." ; This is a documentation string.
(- X))
```