code: def filter_thumbnail_files(chan_path, filenames, metadata_provider):
      
      thumbnail_files_to_skip = metadata_provider.get_thumbnail_paths()
      filenames_cleaned = []
      for filename in filenames:
          keep = True
          chan_filepath = os.path.join(chan_path, filename)
          chan_filepath_tuple = path_to_tuple(chan_filepath)
          if chan_filepath_tuple in thumbnail_files_to_skip:
              keep = False
          if keep:
              filenames_cleaned.append(filename)
      return filenames_cleaned
docs: We don't want to create `ContentNode` from thumbnail files.