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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 _find_newest_ckpt(ckpt_dir):
 """Returns path to most recently modified checkpoint."""

    full_paths = [
        os.path.join(ckpt_dir, fname) for fname in os.listdir(ckpt_dir)
        if fname.startswith("experiment_state") and fname.endswith(".json")
    ]
    return max(full_paths)