code: def guess_dir_structure(dir):
          
          subdir = os.listdir(dir)[0]
          # find a subdir starting with 'n'
          if subdir.startswith('n') and \
                  os.path.isdir(os.path.join(dir, subdir)):
              dir_structure = 'train'
          else:
              dir_structure = 'original'
          logger.info(
              "[ILSVRC12] Assuming directory {} has '{}' structure.".format(
                  dir, dir_structure))
          return dir_structure
docs: Return the directory structure of "dir".
  
          Args:
              dir(str): something like '/path/to/imagenet/val'
  
          Returns:
              either 'train' or 'original'