JOSNDatasets.get_class_weights

[LecongXiong]

https://github.com/ziplab/SPT/blob/e385f67ef0cba524b44072d52ec0650a7022f4e2/lib/datasets.py#L147 the line of code helps each class id appear only once in _class_ids,so what is the meaning of the following line of code?is there a problem with the code? https://github.com/ziplab/SPT/blob/e385f67ef0cba524b44072d52ec0650a7022f4e2/lib/datasets.py#L179 thank you in advance