Advanced

;; An SXML is: (cons Symbol (cons Attributes LSXML))
;;
;; A LSXML is one of:
;; -- empty
;; -- (cons String LSXML)
;; -- (conns SXML LSXML)
;;
;; Attributes are:
;; -- empty
;; -- (cons (list Symbol String) Attributes)
;;
;; interpretation: an SXML corresponds to a pair of tags, 
;; designated by the leading Symbol; the Attributes are
;; the tag's attributes, e.g.,
;;   <font color="red"> ... </font>
;; would be represented as
;;   '(font ((color "red")) ...)
;;
;; a LSXML corresponds to the items that may appear 
;; between the start and end tag

Solution:

;; [PTS 2: note the empty]
(list 'blockquote empty
        "a"
        "b"
        (blockquote empty
          "c"
          "d")
        "e")
;; or with quote and cons