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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def guess_dir_structure(dir):
 """ Return the directory structure of "dir". Args: dir(str):
 something like '/path/to/imagenet/val' Returns: either 'train' or 'original' """

        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