public Signal fetchSignal() throws NullPointerException {
public synchronized Signal fetchSignal() throws NullPointerException {
    public Signal fetchSignal() throws NullPointerException {        Signal s = null;        SignalMemory mem = (SignalMemory) get(Component.SIGNAL_MEMORY);        if (mem != null) {            s = mem.fetchSignal();        } else {            throw new NullPointerException("Could not place signal. The signal memory is null.");        }                return s;    }