AttributeError: module '_pickle' has no attribute 'HIGHEST_PROTOCOL'

[Ronzhen]

How do you solve this problem?
improved_wgan_training-master/tflib/plot.py", line 46, in flush
pickle.dump(dict(_since_beginning), f, pickle.HIGHEST_PROTOCOL)
AttributeError: module '_pickle' has no attribute 'HIGHEST_PROTOCOL'

Thank you

[sh-s-AI]

@Ronzhen replace -1 instead of HIGHEST_PROTOCOL :
pickle.dump(dict(_since_beginning), f, -1)