* xml and n3

introduce org-babel to =xml= and =n3=
#+begin_src emacs-lisp :results silent
  (org-babel-add-interpreter "xml")
  (org-babel-add-interpreter "n3")
#+end_src

if say =n3= should be edited using =xml-mode=, then evaluate the
following adding this pair to =org-src-lang-modes=
#+begin_src emacs-lisp :results silent
  (add-to-list 'org-src-lang-modes '("n3" . xml))
#+end_src

inform org-babel-tangle of their existence and file extensions
#+begin_src emacs-lisp :results silent
  (add-to-list 'org-babel-tangle-langs '("xml" "xml" nil t))
  (add-to-list 'org-babel-tangle-langs '("n3" "n3" nil t))
#+end_src

#+begin_src xml :tangle example
  <first>
  </first>
#+end_src

#+begin_src n3 :tangle example
  n3 stuff
#+end_src