tokens: It all works fine on Mac OS X Lion , but for some reason , an error occurs on Snow Leopard an sooner versions of Mac OS X .
ner_tags: O O O O O B-Operating_System I-Operating_System I-Operating_System B-Version O O O O O O O O O O B-Version I-Version O O O O B-Operating_System I-Operating_System I-Operating_System O