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<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://hs-syutto.com/2018/11/21/%E6%96%B0%E7%AF%89%E7%BE%8E%E8%A3%85%E3%81%A8%E9%81%93%E3%81%AE%E9%A7%85%E3%80%82/>