如何将`.via()`减少一个自定义GraphStage序列？

import akka.actor.ActorSystem
import akka.stream.scaladsl.{Flow, Sink, Source}
import akka.stream.{ActorMaterializer, Graph, GraphStage, GraphStageLogic, Inlet, Outlet}

object CustomGraphStageExample extends App {
  // 创建一个自定义的GraphStage
  class CustomStage extends GraphStage[FlowShape[Int, String]] {
    val in: Inlet[Int] = Inlet("CustomStage.in")
    val out: Outlet[String] = Outlet("CustomStage.out")
    val shape: FlowShape[Int, String] = FlowShape.of(in, out)

    override def createLogic(inheritedAttributes: Attributes): GraphStageLogic = new GraphStageLogic(shape) {
      setHandler(in, new InHandler {
        override def onPush(): Unit = {
          val element = grab(in)
          val transformedElement = element.toString
          push(out, transformedElement)
        }
      })

      setHandler(out, new OutHandler {
        override def onPull(): Unit = {
          pull(in)
        }
      })
    }
  }

  // 创建一个ActorSystem和ActorMaterializer
  implicit val system: ActorSystem = ActorSystem("CustomGraphStageExample")
  implicit val materializer: ActorMaterializer = ActorMaterializer()

  // 创建一个数据流，并通过自定义GraphStage进行转换
  val source = Source(1 to 10)
  val customStage = new CustomStage
  val sink = Sink.foreach[String](println)

  val graph: Graph[FlowShape[Int, String], _] = Flow.fromGraph(customStage)
  val runnableGraph = source.via(graph).to(sink)

  // 运行数据流
  runnableGraph.run()

  // 关闭ActorSystem
  system.terminate()
}