throw new IllegalArgumentException("Only pass a single Consumer, Function, Runnable, or Callable");
}
final Object arg = args[0];
Registration reg = null;
if(Consumer.class.isInstance(arg)) {
reg = reactor.on(sel, (Consumer)arg);
} else if(Function.class.isInstance(arg)) {
reg = reactor.receive(sel, (Function)arg);
} else if(Runnable.class.isInstance(arg)) {