Programmatically add TODO labels in org-mode

gistfile1.txt

(defun org-todo-per-file-keywords (kwds)
  "Sets per file TODO labels. Takes as argument a list of strings to be used as
labels."
  (let (alist)
    (push "TODO" alist)
    (dolist (kwd kwds)
      (push kwd alist))
    (setq alist (list (nreverse alist)))
    ;; TODO keywords.
    (setq-local org-todo-kwd-alist nil)
    (setq-local org-todo-key-alist nil)
    (setq-local org-todo-key-trigger nil)
    (setq-local org-todo-keywords-1 nil)
    (setq-local org-done-keywords nil)
    (setq-local org-todo-heads nil)
    (setq-local org-todo-sets nil)
    (setq-local org-todo-log-states nil)
    (let ((todo-sequences alist))
      (dolist (sequence todo-sequences)
	(let* ((sequence (or (run-hook-with-args-until-success
			      'org-todo-setup-filter-hook sequence)
			     sequence))
	       (sequence-type (car sequence))
	       (keywords (cdr sequence))
	       (sep (member "|" keywords))
	       names alist)
	  (dolist (k (remove "|" keywords))
	    (unless (string-match "^\\(.*?\\)\\(?:(\\([^!@/]\\)?.*?)\\)?$"
				  k)
	      (error "Invalid TODO keyword %s" k))
	    (let ((name (match-string 1 k))
		  (key (match-string 2 k))
		  (log (org-extract-log-state-settings k)))
	      (push name names)
	      (push (cons name (and key (string-to-char key))) alist)
	      (when log (push log org-todo-log-states))))
	  (let* ((names (nreverse names))
		 (done (if sep (org-remove-keyword-keys (cdr sep))
			 (last names)))
		 (head (car names))
		 (tail (list sequence-type head (car done) (org-last done))))
	    (add-to-list 'org-todo-heads head 'append)
	    (push names org-todo-sets)
	    (setq org-done-keywords (append org-done-keywords done nil))
	    (setq org-todo-keywords-1 (append org-todo-keywords-1 names nil))
	    (setq org-todo-key-alist
		  (append org-todo-key-alist
			  (and alist
			       (append '((:startgroup))
				       (nreverse alist)
				       '((:endgroup))))))
	    (dolist (k names) (push (cons k tail) org-todo-kwd-alist))))))
    (setq org-todo-sets (nreverse org-todo-sets)
	  org-todo-kwd-alist (nreverse org-todo-kwd-alist)
	  org-todo-key-trigger (delq nil (mapcar #'cdr org-todo-key-alist))
	  org-todo-key-alist (org-assign-fast-keys org-todo-key-alist))
    ;; Compute the regular expressions and other local variables.
    ;; Using `org-outline-regexp-bol' would complicate them much,
    ;; because of the fixed white space at the end of that string.
    (unless org-done-keywords
      (setq org-done-keywords
	    (and org-todo-keywords-1 (last org-todo-keywords-1))))
    (setq org-not-done-keywords
	  (org-delete-all org-done-keywords
			  (copy-sequence org-todo-keywords-1))
	  org-todo-regexp (regexp-opt org-todo-keywords-1 t)
	  org-not-done-regexp (regexp-opt org-not-done-keywords t)
	  org-not-done-heading-regexp
	  (format org-heading-keyword-regexp-format org-not-done-regexp)
	  org-todo-line-regexp
	  (format org-heading-keyword-maybe-regexp-format org-todo-regexp)
	  org-complex-heading-regexp
	  (concat "^\\(\\*+\\)"
		  "\\(?: +" org-todo-regexp "\\)?"
		  "\\(?: +\\(\\[#.\\]\\)\\)?"
		  "\\(?: +\\(.*?\\)\\)??"
		  "\\(?:[ \t]+\\(:[[:alnum:]_@#%:]+:\\)\\)?"
		  "[ \t]*$")
	  org-complex-heading-regexp-format
	  (concat "^\\(\\*+\\)"
		  "\\(?: +" org-todo-regexp "\\)?"
		  "\\(?: +\\(\\[#.\\]\\)\\)?"
		  "\\(?: +"
		  ;; Stats cookies can be stuck to body.
		  "\\(?:\\[[0-9%%/]+\\] *\\)*"
		  "\\(%s\\)"
		  "\\(?: *\\[[0-9%%/]+\\]\\)*"
		  "\\)"
		  "\\(?:[ \t]+\\(:[[:alnum:]_@#%%:]+:\\)\\)?"
		  "[ \t]*$")
	  org-todo-line-tags-regexp
	  (concat "^\\(\\*+\\)"
		  "\\(?: +" org-todo-regexp "\\)?"
		  "\\(?: +\\(.*?\\)\\)??"
		  "\\(?:[ \t]+\\(:[[:alnum:]:_@#%]+:\\)\\)?"
		  "[ \t]*$"))
    (org-compute-latex-and-related-regexp)))

;; example of usage
(org-todo-per-file-keywords '("label 1" "label 2" "something" "last one"))