       (save-match-data
         (when (and
                (>= (length file-name) 2)
-               (not (= (string-to-int (s-left 2 file-name))
-                       0))
                (let ((case-fold-search t))
                  (string-match (rx
                                 (group "<span class=\"section-number-"

              (format "\n<pre class=\"src src-%s\"%s>%s</pre>" lang label code))))))))
(setq org-confirm-babel-evaluate nil)

(defun lean-filter-headline (text backend info)
  "Adjust the chapter number based on the filename. For example,
when the filename is '07_Induction_and_Recursion.org', it uses

                                (group (* (char digit ".")))
                                (group "</span>"))
                               text)))
          (replace-match (format "\\1 %s\\3\\4"
                                 (lean-extract-chapter-name (s-left 2 file-name)))
                         t nil text))))))

(defun lean-filter-html-link (text backend info)
