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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 _is_cache_dir_appropriate(cache_dir, cache_file):
 """ Determine if a directory is acceptable for building. A directory is suitable if any of the following are true: - it doesn't exist - it is empty - it contains an existing build cache """

    if os.path.exists(cache_dir):
        files = os.listdir(cache_dir)
        if cache_file in files:
            return True
        return not bool(files)
    return True