code: def isValid(folder, epoch=0):
      
      # Validate by checking for the training 'silence.pkl' on the given epoch
      # This file is unique to our pre-processed dataset generated by 'process_dataset.py'
      return os.path.exists(os.path.join(folder, str(epoch), "train", "silence.pkl"))
docs: Check if the given folder is a valid preprocessed dataset