LEXICAL VARIABLES GENERATORS AND ENCAPSULATION---------------------------------------LETS PRODUCE NESTED FENCES(defun both-ends-with-let (whole-list)  (let ((leading (first whole-list))             ;Bind LEADING.        (trailing (first (last whole-list))))    ;Bind TRAILING.    (list leading trailing)))(defun both-ends-with-funny-let (whole-list)  (let (leading trailing)                        ;Bind both to NIL.    (setf leading (first whole-list)             ;Assign new value.    (setf trailing (first (last whole-list)))    ;Assign new value.    (list leading trailing)))                    ;Combine.-------------------------------------------------------------------NESTED FENCES PROVIDE VARIABLE VALUES