def test_threads():

       gw = py.execnet.PopenGateway()

       gw.remote_init_threads(3)

       c1 = gw.remote_exec("channel.send(channel.receive())")

       c2 = gw.remote_exec("channel.send(channel.receive())")

->     c2.send(1)

       res = c2.receive()

       assert res == 1

       c1.send(42)

       res = c1.receive()

       assert res == 42

       gw.exit()