code: func NewPublicFilterAPI(backend Backend, lightMode bool) *PublicFilterAPI {
  	api := &PublicFilterAPI{
  		backend: backend,
  		mux:     backend.EventMux(),
  		chainDb: backend.ChainDb(),
  		events:  NewEventSystem(backend.EventMux(), backend, lightMode),
  		filters: make(map[rpc.ID]*filter),
  	}
  	go api.timeoutLoop()
  
  	return api
  }
docs: // NewPublicFilterAPI returns a new PublicFilterAPI instance.