val a1 = client.newCall(newRequest("http://a/1"))
    val a2 = client.newCall(newRequest("http://a/2"))
    val a3 = client.newCall(newRequest("http://a/3"))
    val a4 = client.newCall(newRequest("http://a/4"))
    val a5 = client.newCall(newRequest("http://a/5"))
    a1.enqueue(callback)
    a2.enqueue(callback)
    a3.enqueue(callback)
    a4.enqueue(callback)
    a5.enqueue(callback)