client =
      client.newBuilder()
        .dispatcher(dispatcher)
        .build()
    val requestA = Request(server.url("/a"))
    val requestB = Request(server.url("/b"))
    val callA = client.newCall(requestA)
    val callB = client.newCall(requestB)
    server.dispatcher =
      object : mockwebserver3.Dispatcher() {
        var nextResponse = 'A'