This data coul d come from a fetch OR from ldp comtaimner
function (kb, x, displayables) {
      var t = kb.findTypeURIs(subject)
      for (var k = 0; k < displayables.length; k++) {
        if ($rdf.Util.mediaTypeClass(displayables[k]).uri in t) {
          return true
        }
      }
      return false
    }