Watchers

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  Christopher Walston

  https://inventmag.com/%EC%8A%A4%ED%94%BC%EB%93%9C%ED%82%A4%EB%85%B8-%ED%99%95%EB%A5%A0-%EB%B6%84%EC%84%9D-%EB%8D%94%EC%9A%B1-%EC%8A%A4%EB%A7%88%ED%8A%B8%ED%95%9C-%EA%B2%8C%EC%9E%84%EC%9D%84-%EC%9C%84%ED%95%9C-%EA%B0%80/