function t1 () { var i = 0; while (1) {print ("t1"+i++); coroutine.lthread_sleep();}}
function t2 () { var i = 0; while (1) {print ("t2"+i++); coroutine.lthread_sleep();}}
co = coroutine.lthread_create(t1);
co2 = coroutine.lthread_create(t2);
coroutine.lthread_resume(co);
coroutine.lthread_resume(co2);
coroutine.lthread_resume(co);