message: get true for is* functions'
diff: <h2 id="isAudio"><a href="#isAudio">isAudio</a></h2>
  <script id="script-isAudio">
  window.addEventListener('DOMContentLoaded', (event) => {
  - UI.store.add(UI.rdf.namedNode('http://example.com/audio.mpeg'), UI.ns.rdf('type'), UI.rdf.namedNode('http://www.w3.org/ns/iana/media-types/audio'))
  + UI.store.add(UI.rdf.namedNode('http://example.com/audio.mpeg'), UI.ns.rdf('type'), UI.rdf.namedNode('http://www.w3.org/ns/iana/media-types/audio/'))
  const result = UI.widgets.isAudio(UI.rdf.namedNode('http://example.com/audio.mpeg'))
  $('#div-isAudio').appendChild(document.createTextNode(result))
  })
  <h2 id="isImage"><a href="#isImage">isImage</a></h2>
  <script id="script-isImage">
  window.addEventListener('DOMContentLoaded', (event) => {
  - UI.store.add(UI.rdf.namedNode('http://example.com/image.jpeg'), UI.ns.rdf('type'), UI.rdf.namedNode('http://www.w3.org/ns/iana/media-types/image'))
  + UI.store.add(UI.rdf.namedNode('http://example.com/image.jpeg'), UI.ns.rdf('type'), UI.rdf.namedNode('http://www.w3.org/ns/iana/media-types/image/'))
  const result = UI.widgets.isImage(UI.rdf.namedNode('http://example.com/image.jpeg'))
  $('#div-isImage').appendChild(document.createTextNode(result))
  })
  <h2 id="isVideo"><a href="#isVideo">isVideo</a></h2>
  <script id="script-isVideo">
  window.addEventListener('DOMContentLoaded', (event) => {
  - UI.store.add(UI.rdf.namedNode('http://example.com/video.mov'), UI.ns.rdf('type'), UI.rdf.namedNode('http://www.w3.org/ns/iana/media-types/video'))
  + UI.store.add(UI.rdf.namedNode('http://example.com/video.mov'), UI.ns.rdf('type'), UI.rdf.namedNode('http://www.w3.org/ns/iana/media-types/video/'))
  const result = UI.widgets.isImage(UI.rdf.namedNode('http://example.com/video.mov'))
  $('#div-isVideo').appendChild(document.createTextNode(result))
  })
  