code: def __preprocess(self):
      if not self.__files_exist(self._processed_file_paths):
          self.__make_directory(self._processed_directory)
          self._process()
  
file_path: AutoGL/autogl/datasets/_data_source.py
imports: import os
  import typing
label_desc: Use image node_id 12 for calling the OnlineDataSource obj's underlying member method code with example usage: obj.__preprocess() without return types