// Jump to 'l' if this arg is not null. If null, fall through and build the default value!
Label l = s.getNewLabel();
LocalAsgnNode n = (LocalAsgnNode)optArgs.get(j);
Variable av = s.getLocalVariable(n.getName());
s.addInstr(new ReceiveOptionalArgumentInstr(av, argIndex));
s.addInstr(new BNEInstr(av, Nil.NIL, l)); // if 'av' is not null, go to default
build(n, s);
s.addInstr(new LABEL_Instr(l));
}
}