+(defun uso-unique-codes (usos)
+ (let ((sab-codes (make-hash-table :test 'equal)))
+ (dolist (uso usos)
+ (setf (gethash (sab uso) sab-codes) (code uso)))
+ (loop for key being the hash-key in sab-codes
+ collect (list key (gethash key sab-codes)))))
+
+