NameError: name 'varnames2check' is not defined error with utils/metadata.py

I started to use our new variables (2t,tcc,msl) for data preprocessing step. The error raised as below: Traceback (most recent call last): File "../main_scripts/main_preprocess_data_step1.py", line 219, in main() File "../main_scripts/main_preprocess_data_step1.py", line 104, in main variables=vars) File "/p/project/deepacf/deeprain/bing/ambs/video_prediction_tools/utils/metadata.py", line 71, in init MetaData.get_and_set_metadata_from_file(self, suffix_indir, exp_id, data_filename, slices, variables) File "/p/project/deepacf/deeprain/bing/ambs/video_prediction_tools/utils/metadata.py", line 118, in get_and_set_metadata_from_file MetaData.check_datafile(datafile, variables) File "/p/project/deepacf/deeprain/bing/ambs/video_prediction_tools/utils/metadata.py", line 395, in check_datafile for i in range(len(varnames2check)): NameError: name 'varnames2check' is not defined

the varnames2check is in the staticmethod "check_datafile", where the varnames2check is not predefined.