Semantic keys when needed

[Andrea Crotti <andrea.crotti.0@gmail.com>]

First I add some global keys set for semantic but given that is not
supported everywhere now I use

--8<---------------cut here---------------start------------->8---
(defun activate-more-semantic-bindings ()
  "add some other nice bindings to modes supported by semantic"
  (interactive)
  (local-set-key (kbd "M-n") 'senator-next-tag)
  (local-set-key (kbd "M-p") 'senator-previous-tag)
  (local-set-key [f6] 'senator-fold-tag-toggle)
  ;; narrows to the actual function or class analyzed
  ;; C-x n w to widen again
  (local-set-key "\C-xnn" 'semantic-narrow-to-tag)
  (local-set-key "\M-." 'semantic-complete-jump)
  (local-set-key "\M-?" 'semantic-ia-fast-jump))
--8<---------------cut here---------------end--------------->8---

and I activate it only with some modes...
But isn't it possible to activate it WHEN semantic is supported?
"semantic-mode" is nil also when is actually supported (c/python) but I
think there must be a way to see where is supported, any hints?