set(arg, m.getKey(), obj);
if (e instanceof SetEvent) { SetEvent se = (SetEvent) e; Object prev = se.getPreviousValue(); if (prev != null) { set(prev, m.getKey(), null); } }  if (arg != null) { set(arg, m.getKey(), obj); }
            public void onJoinFrom(JoinFrom m) {                set(arg, m.getKey(), obj);            }