How to use the rdflib.Query function in rdflib

function generateQuery (type) {
    var query = new $rdf.Query()
    var rowVar = kb.variable(keyVariable.slice(1)) // don't pass '?'

    addSelectToQuery(query, type)
    addWhereToQuery(query, rowVar, type)
    addColumnsToQuery(query, rowVar, type)

    return query
  }

var renderTrip = function renderTrip (subject, thisDiv) {
      var query = new $rdf.Query(UI.utils.label(subject))
      var vars = ['date', 'transaction', 'comment', 'type', 'in_USD']
      var v = {}
      vars.map(function (x) {
        query.vars.push((v[x] = $rdf.variable(x)))
      }) // Only used by UI
      query.pat.add(v.transaction, TRIP('trip'), subject)

      var opt = kb.formula()
      opt.add(v.transaction, ns.rdf('type'), v.type) // Issue: this will get stored supertypes too
      query.pat.optional.push(opt)

      query.pat.add(v.transaction, UI.ns.qu('date'), v.date)

      opt.add(v.transaction, ns.rdfs('comment'), v.comment)
      query.pat.optional.push(opt)