Cacher is the code snippet organizer for pro developers

(setq org-file-apps
      '(;; Web Pages
        ("\.x?html?\\'" . "firefox %s")
        ;; PDF (disable this because I use package `org-pdfview'.
        ;; ("\\.pdf\\'" . auto-mode)
        ;; ("\\.pdf::\\([[:digit:]]+\\)\\'" . auto-mode)
        ;; disable this, to use `doc-view' from `pdf-tools' for PDF.
        ;; ("\\.pdf\\'" . "okular %s")
        ;; ("\\.pdf::\\([[:digit:]]+\\)\\'" . "okular -p %1 %s")
        ;; CHM
        ("\\.chm\\'" . "kchmviewer %s")
        ;; EBooks
        ("\\.epub\\'" . "okular %s")
        ("\\.mobi\\'" . "okular %s")
        ("\\.azw3\\'" . "okular %s")
        ;; Image
        ("\\.png\\'" . "sxiv %s")
        ;; ("\\.jp\(e\)?g" . "sxiv %s")
        ("\\.jpg\\'" . "sxiv %s")
        ("\\.jpeg\\'" . "sxiv %s")
        ("\\.gif\\'" . (lambda (file link)
                         (let (image-var (create-image file))
                           (with-temp-buffer-window
                            "*Org-mode animated gif image*"
                            (progn
                              (insert-image my-image)
                              ;; (image-animate my-image 0 t)
                              )
                            (delete-window nil)
                            ))))
        ;; ("\\.gif\\'" . "sxiv -a -f %s") ; "sxiv -a -f -- %s
        ;; ("\\.gif\\'" . "gwenview %s")
        ;; ("\\.svg\\'" . "feh --magick-timeout 5 %s")
        ("\\.svg\\'" . "nomacs %s")
        ;; Mind Maps
        ("\\.mm\\'" . "freemind %s") ; freeplane
        ;; Office
        ;; Open Text Document
        ("\\.odt\\'" . "libreoffice %s") ; Text Documentation
        ("\\.ods\\'" . "libreoffice %s") ; Spreadsheet
        ("\\.odp\\'" . "libreoffice %s") ; Presentation
        ("\\.odf\\'" . "libreoffice %s") ; Database / Formula
        ;; Video
        ("\\.mp4\\'" . "mpv %s")
        ("\\.mov\\'" . "mpv %s")
        ("\\.ogv\\'" . "mpv %s")
        ;; Audio
        ("\\.mp3\\'" . "mpg123 %s")
        ("\\.ogg\\'" . "mpv %s")
        (auto-mode . emacs)
        ))