{"id":1,"op":"serialize_label","payload":{"label_text":"{\"img_name\":\"x.jpg\",\"infos\":[{\"id\":\"a\",\"class\":\"b\",\"shape\":\"rectangle\",\"points\":[[1,2],[3,4]]}],\"bindings\":[]}"}}
{"id":2,"op":"serialize_label","payload":{"label_text":"{\"img_name\":\"x.jpg\",\"infos\":[{\"id\":\"a\",\"class\":\"b\",\"shape\":\"diamond\",\"points\":[[1,2],[3,4]]}],\"bindings\":[]}"}}
{"id":3,"op":"serialize_label","payload":{"label_text":"{\"img_name\":\"x.jpg\",\"infos\":[{\"id\":\"a\",\"shape\":\"rectangle\",\"points\":[[1,2],[3,4]]}],\"bindings\":[]}"}}
{"id":4,"op":"serialize_label","payload":{"label_text":"{\"img_name\":\"x.jpg\",\"infos\":[],\"bindings\":[]}"}}
{"id":5,"op":"serialize_label","payload":{"label_text":"{ this is not json"}}
