;; Our pretty-printing function
(let ((previous ""))
  (defun pretty-print ()
    (letrec ((title (org-entry-get nil "ITEM"))
             (year (org-entry-get nil "year"))
             (comment (org-entry-get nil "comment")))
      (format "- %s %s%s"
              (if (equal previous year)
                  "---"
                (setq previous year))
              title
            (if comment
                (format " (%s)" comment)
              "")
            )))
  (string-join (org-map-entries 'pretty-print nil '("../#teaching.org")) "\n"))