Can not open pdm_models

[nuran]

I am trying to open pdm_models. But when I try to open these files I am getting and error as below.

pdm_clm_functions.py", line 158, in feature_based_pdm_corr
pdm_temp = pickle.load(filehandler)
ModuleNotFoundError: No module named 'copy_reg\r'

Any idea why I can not load these models. I tried using python 2 and 3 both.

Thank you in advance.