Convert tabs to spaces in Emacs

tab2space.el

;;; Turn tabs to spaces
(defun tabs-to-spaces (&optional begin end)
  "Turn all tabs in a region into four spaces."
  (interactive "r")
  (save-excursion
	  (if mark-active 
		  (replace-regexp "\t" "    " nil (point) (mark))
		(replace-regexp "\t" "    " nil (point-min) (point-max))
		)		
	  )
 )