code: function setModifiedDate (subj, kb, doc) {
        if (SET_MODIFIED_DATES) {
          if (!getOption(tracker, 'trackLastModified')) return
          var deletions = kb.statementsMatching(subject, DCT('modified'))
          deletions = deletions.concat(kb.statementsMatching(subject, WF('modifiedBy')))
          var insertions = [ $rdf.st(subject, DCT('modified'), new Date(), doc) ]
          if (me) insertions.push($rdf.st(subject, WF('modifiedBy'), me, doc))
          updater.update(deletions, insertions, function (uri, ok, body) {})
        }
      }
docs: Don't bother changing the last modified dates of things: save time