private DataMessage searchMessage(ArrayList<DataMessage> stored,
            Address source, int seqNbr) {
        Iterator<DataMessage> iter = stored.iterator();
        while (iter.hasNext()) {
            DataMessage dataMessage = iter.next();
            if (dataMessage.getSequenceNumber() == seqNbr
                    && dataMessage.getSource() == source) {
                return dataMessage;
            }
        }
        return null;
    }