bind f1, f2, f3 and f4 in emacs term

*scratch*

(defun term-send-function-key ()
  (interactive)
  (let* ((char last-input-event)
         (output (cdr (assoc char term-function-key-alist))))
    (term-send-raw-string output)))

(defconst term-function-key-alist '((f1 . "\e[OP")
                                    (f2 . "\e[OQ")
                                    (f3 . "\e[OR")
                                    (f4 . "\e[OS")))

(dolist (spec term-function-key-alist)
  (define-key term-raw-map
    (read-kbd-macro (format "<%s>" (car spec)))
    'term-send-function-key))