func (it *Materialize) materializeSet() {
	i := 0
	for graph.Next(it.subIt) {
		i++
		if i > abortMaterializeAt {
			it.aborted = true
			break
		}
		id := it.subIt.Result()
		val := graph.ToKey(id)
		if _, ok := it.containsMap[val]; !ok {
			it.containsMap[val] = len(it.values)
			it.values = append(it.values, nil)
		}
		index := it.containsMap[val]
		tags := make(map[string]graph.Value)
		it.subIt.TagResults(tags)
		it.values[index] = append(it.values[index], result{id: id, tags: tags})
		it.actualSize += 1
		for it.subIt.NextPath() {
			i++
			if i > abortMaterializeAt {
				it.aborted = true
				break
			}
			tags := make(map[string]graph.Value)
			it.subIt.TagResults(tags)
			it.values[index] = append(it.values[index], result{id: id, tags: tags})
			it.actualSize += 1
		}
	}
	it.err = it.subIt.Err()
	if it.err == nil && it.aborted {
		if glog.V(2) {
			glog.V(2).Infoln("Aborting subiterator")
		}
		it.values = nil
		it.containsMap = nil
		it.subIt.Reset()
	}
	it.hasRun = true
}
func (it *Materialize) Contains(v graph.Value) bool {
	graph.ContainsLogIn(it, v)
	it.runstats.Contains += 1
	if !it.hasRun {
		it.materializeSet()
	}
	if it.err != nil {
		return false
	}
	if it.aborted {
		return it.subIt.Contains(v)
	}
	key := graph.ToKey(v)
	if i, ok := it.containsMap[key]; ok {
		it.index = i
		it.subindex = 0
		return graph.ContainsLogOut(it, v, true)
	}
	return graph.ContainsLogOut(it, v, false)
}