Item mem = (Item) getChild(SystemItem.SIGNAL_MEMORY);
Item mem = getChild(SystemItem.SIGNAL_MEMORY);
    public void storeSignal(Signal s) throws Exception {        Item mem = (Item) getChild(SystemItem.SIGNAL_MEMORY);        if (mem != null) {            Array n = mem.buildName(SystemItem.SIGNAL);            mem.setChild(n, s);        } else {            throw new Exception("Could not store signal. The signal memory is null.");        }    }