* repr's:
** ConcBlockingQueue
** AsyncTask
** Uninstantiable
* nqp::op's:
** Threads:    	  threadyield (current tests are flaky)
** ConcQueues:    queuepoll
** Timers:     	  timer
** Cancellations: cancel
** Signals:       signal
** Watches:       watchfile
** AsyncIO:       asyncconnect, asynclisten, asyncwritestr,
                  asyncwritebytes, asyncreadchars, asyncreadbytes
** AsyncProcs:    spawnprocasync, killprocasync
* Situations:
** Serialization / precompilation
** Signal interaction with locks/condvars/semaphores/timers/etc.
** Stress testing
