can't pickle dict_keys objects.

I chose to use multiple GPU for training,I found a problem.The question:type: can not pickle dict_keys objects.
I don't know how to solve it，After checking, this problem only occurs on Windows system, but I use ubuntu system
Could you tell me how to solve it?，Thank you

Hello,

I also encountered the same issue and it was resolved by replacing this line character.py 56 with self.labels = list(self.vocab_dict.keys())