Function: SET-FLAG

Source

(defun set-flag (value flag &optional (flag-system *current-flag-system*))
  (cond ((and (listp flag) (not (null flag)))
	 (set-flag (set-flag value (cdr flag) flag-system)
		   (car flag)
		   flag-system))
	((not (null flag))
	 (logior value (flag-value flag flag-system)))
	(t value)))