Set newlit = new HashSet(literals.size());
Iterator it = literals.iterator();
while (it.hasNext())
{
GroundEffect e = (GroundEffect) it.next();
if (! (e instanceof NullEffect)) newlit.add(e.staticifyEffect(fValues));
}
literals = newlit;
if (literals.isEmpty()) return NullEffect.getInstance();
else return this;
}